From 2ced0d02b3ba77ee2358e94b8907baab03ceee51 Mon Sep 17 00:00:00 2001 From: Rex Jaeschke Date: Mon, 13 Nov 2023 11:05:27 -0500 Subject: [PATCH 01/10] Add support for extending partial methods fix md formatting revert to previous text handle imp/exp private allow partial with ref_kind returns change link's target name --- standard/classes.md | 63 +++++++++++++++++++++++++++++++++------------ 1 file changed, 47 insertions(+), 16 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index 199e77de3..5dad9879c 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -2074,7 +2074,7 @@ ref_kind ; ref_method_modifiers - : ref_method_modifier* + : ref_method_modifier* 'partial'? ; method_header @@ -2151,7 +2151,8 @@ A declaration has a valid combination of modifiers if all of the following are t - The declaration may include the `abstract` and `override` modifiers so that an abstract member may override a virtual member. - If the declaration includes the `private` modifier, then the declaration does not include any of the following modifiers: `virtual`, `override`, or `abstract`. - If the declaration includes the `sealed` modifier, then the declaration also includes the `override` modifier. -- If the declaration includes the `partial` modifier, then it does not include any of the following modifiers: `new`, `public`, `protected`, `internal`, `private`, `virtual`, `sealed`, `override`, `abstract`, or `extern`. +- If the declaration includes the `partial` modifier, then it does not include the modifier `abstract`. +- If the declaration is for a restricted partial method ([§15.6.9](classes.md#1569-partial-methods)), then it does not include any of the following modifiers: `new`, `public`, `protected`, `internal`, `private`, `virtual`, `sealed`, `override`, or `extern`. Methods are classified according to what, if anything, they return: @@ -2159,7 +2160,7 @@ Methods are classified according to what, if anything, they return: - Otherwise, if *return_type* is `void`, the method is ***returns-no-value*** and does not return a value; - Otherwise, the method is ***returns-by-value*** and returns a value. -The *return_type* of a returns-by-value or returns-no-value method declaration specifies the type of the result, if any, returned by the method. Only a returns-no-value method may include the `partial` modifier ([§15.6.9](classes.md#1569-partial-methods)). If the declaration includes the `async` modifier then *return_type* shall be `void` or the method returns-by-value and the return type is a *task type* ([§15.14.1](classes.md#15141-general)). +The *return_type* of a returns-by-value or returns-no-value method declaration specifies the type of the result, if any, returned by the method. Only a returns-no-value method may include the `partial` modifier ([§15.6.9](classes.md#1569-partial-methods)). If the declaration includes the `async` modifier then *return_type* for a restricted partial method shall be `void` or the method returns-by-value and the return type is a *task type* ([§15.14.1](classes.md#15141-general)). The *ref_return_type* of a returns-by-ref method declaration specifies the type of the variable referenced by the *variable_reference* returned by the method. @@ -2388,7 +2389,7 @@ For a `struct` type, within an instance method, instance accessor ([§12.2.1](ex A parameter declared with an `out` modifier is an ***output parameter***. For definite-assignment rules, see [§9.2.7](variables.md#927-output-parameters). -A method declared as a partial method ([§15.6.9](classes.md#1569-partial-methods)) shall not have output parameters. +A method declared as a restricted partial method ([§15.6.9](classes.md#1569-partial-methods)) shall not have output parameters. > *Note*: Output parameters are typically used in methods that produce multiple return values. *end note* @@ -3026,23 +3027,53 @@ The mechanism by which linkage to an external method is achieved is implementati ### 15.6.9 Partial methods -When a method declaration includes a `partial` modifier, that method is said to be a ***partial method***. Partial methods may only be declared as members of partial types ([§15.2.7](classes.md#1527-partial-type-declarations)), and are subject to a number of restrictions. +When a *method declaration* includes a `partial` modifier, that method is said to be a ***partial method***. Partial methods may only be declared as members of partial types ([§15.2.7](classes.md#1527-partial-type-declarations)). -Partial methods may be defined in one part of a type declaration and implemented in another. The implementation is optional; if no part implements the partial method, the partial method declaration and all calls to it are removed from the type declaration resulting from the combination of the parts. +Partial methods may be defined in one part of a type declaration and implemented in another, or be defined and implemented in the same part. -Partial methods shall not define access modifiers; they are implicitly private. Their return type shall be `void`, and their parameters shall not be output parameters. The identifier `partial` is recognized as a contextual keyword ([§6.4.4](lexical-structure.md#644-keywords)) in a method declaration only if it appears immediately before the `void` keyword. A partial method cannot explicitly implement interface methods. +There are two kinds of partial method declarations: If the body of the method declaration is a semicolon, the declaration is said to be a ***defining partial method declaration***. Otherwise, the declaration is said to be an ***implementing partial method declaration***. Across the parts of a type declaration, there may be only one defining partial method declaration with a given signature, and there may be only one implementing partial method declaration with a given signature. If an implementing partial method declaration is given, a corresponding defining partial method declaration shall exist, and the declarations shall match as specified in the following: -There are two kinds of partial method declarations: If the body of the method declaration is a semicolon, the declaration is said to be a ***defining partial method declaration***. If the body is other than a semicolon, the declaration is said to be an ***implementing partial method declaration***. Across the parts of a type declaration, there shall be only one defining partial method declaration with a given signature, and there shall be at most only one implementing partial method declaration with a given signature. If an implementing partial method declaration is given, a corresponding defining partial method declaration shall exist, and the declarations shall match as specified in the following: - -- The declarations shall have the same method name, number of type parameters, and number of parameters. -- The declarations shall have the same modifiers (although not necessarily in the same order), with the exception of the `async` modifier which shall not appear on a defining part. -- Corresponding parameters in the declarations shall have the same modifiers (although not necessarily in the same order) and the same types, or identity convertible types (modulo differences in type parameter names). +- The declarations shall have the same modifiers (although not necessarily in the same order), with the exception of the `async` and `extern` modifiers which shall not appear on a defining part. +- In the case of private accessibility, both declarations shall be implicitly private (that is, with no accessibility modifier) or both shall be explicitly `private`. +- Corresponding parameters in the declarations shall have the same modifiers (although not necessarily in the same order) and the same types (modulo differences in type parameter names). - Corresponding type parameters in the declarations shall have the same constraints (modulo differences in type parameter names). -An implementing partial method declaration can appear in the same part as the corresponding defining partial method declaration. +Over time, the specification for partial methods has evolved, resulting in restricted and unrestricted versions. A ***restricted partial method*** has no explicit access modifiers (and is implicitly private), has a `void` return type, and has no out parameters. An ***unrestricted partial method*** is a partial method that has explicit access modifiers, a non-`void` return type, or any out parameters. + +For a restricted partial method, the implementation is optional; if no part implements the partial method, the partial method declaration and all calls to it are removed from the type declaration resulting from the combination of the parts. For an unrestricted partial method both the definition and implementation shall exist. + +In *method_declaration*, the identifier `partial` is recognized as a contextual keyword ([§6.4.4](lexical-structure.md#644-keywords)) only if it immediately precedes the *return_type*. A partial method cannot explicitly implement interface methods. + +> *Example*: +> +> +> ```csharp +> // part containing defining partial method declarations +> partial class C +> { +> partial void M1(); // restricted, impl. optional +> private partial void M2(); // unrestricted, impl. required +> protected partial bool M3(); // unrestricted, impl. required +> public partial void M4(out int i); // unrestricted, impl. required +> } +> +> // part containing implementing partial method declarations +> partial class C +> { +> private partial void M2() { ... } +> protected partial bool M3() { ... } +> public partial void M4(out int i) { ... } +> } +> ``` +> +> *end example* + +Only a defining partial method participates in overload resolution. As such, in the case of a restricted partial method, whether or not an implementing declaration is given, invocation expressions may resolve to invocations of the partial method. -Only a defining partial method participates in overload resolution. Thus, whether or not an implementing declaration is given, invocation expressions may resolve to invocations of the partial method. Because a partial method always returns `void`, such invocation expressions will always be expression statements. Furthermore, because a partial method is implicitly `private`, such statements will always occur within one of the parts of the type declaration within which the partial method is declared. +> *Note*: Because a restricted partial method always returns `void`, such invocation expressions will always be expression statements. Furthermore, because a restricted partial method is implicitly `private`, such statements will always occur within one of the parts of the type declaration within which the partial method is declared. *end note* + + > *Note*: The definition of matching defining and implementing partial method declarations does not require parameter names to match. This can produce *surprising*, albeit *well defined*, behaviour when named arguments ([§12.6.2.1](expressions.md#12621-general)) are used. For example, given the defining partial method declaration for `M` in one file, and the implementing partial method declaration in another file: > > @@ -3065,7 +3096,7 @@ Only a defining partial method participates in overload resolution. Thus, whethe > > *end note* -If no part of a partial type declaration contains an implementing declaration for a given partial method, any expression statement invoking it is simply removed from the combined type declaration. Thus the invocation expression, including any subexpressions, has no effect at run-time. The partial method itself is also removed and will not be a member of the combined type declaration. +If a restricted partial method has no implementation, any expression statement invoking it is simply removed from the combined type declaration. Thus, the invocation expression, including any subexpressions, has no effect at run-time. The partial method itself is also removed and will not be a member of the combined type declaration. If an implementing declaration exists for a given partial method, the invocations of the partial methods are retained. The partial method gives rise to a method declaration similar to the implementing partial method declaration except for the following: @@ -3075,7 +3106,7 @@ If an implementing declaration exists for a given partial method, the invocation - The attributes on the parameters of the resulting method declaration are the combined attributes of the corresponding parameters of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. -If a defining declaration but not an implementing declaration is given for a partial method `M`, the following restrictions apply: +If a defining declaration but not an implementing declaration is given for a restricted partial method `M`, the following restrictions apply: - It is a compile-time error to create a delegate from `M` ([§12.8.17.5](expressions.md#128175-delegate-creation-expressions)). From 89f4c4d10af64524be6509295d4e10e2422b1660 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Thu, 8 Jan 2026 16:28:11 -0500 Subject: [PATCH 02/10] Address existing comments. Also, edit after moving text around. --- standard/classes.md | 75 +++++++++++++++++++++++++++------------------ 1 file changed, 45 insertions(+), 30 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index 5dad9879c..a4da81a98 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -2152,7 +2152,7 @@ A declaration has a valid combination of modifiers if all of the following are t - If the declaration includes the `private` modifier, then the declaration does not include any of the following modifiers: `virtual`, `override`, or `abstract`. - If the declaration includes the `sealed` modifier, then the declaration also includes the `override` modifier. - If the declaration includes the `partial` modifier, then it does not include the modifier `abstract`. -- If the declaration is for a restricted partial method ([§15.6.9](classes.md#1569-partial-methods)), then it does not include any of the following modifiers: `new`, `public`, `protected`, `internal`, `private`, `virtual`, `sealed`, `override`, or `extern`. +- If the declaration is for a restricted partial method (§restricted-partial-methods), then it does not include any of the following modifiers: `new`, `public`, `protected`, `internal`, `private`, `virtual`, `sealed`, `override`, or `extern`. Methods are classified according to what, if anything, they return: @@ -2160,7 +2160,7 @@ Methods are classified according to what, if anything, they return: - Otherwise, if *return_type* is `void`, the method is ***returns-no-value*** and does not return a value; - Otherwise, the method is ***returns-by-value*** and returns a value. -The *return_type* of a returns-by-value or returns-no-value method declaration specifies the type of the result, if any, returned by the method. Only a returns-no-value method may include the `partial` modifier ([§15.6.9](classes.md#1569-partial-methods)). If the declaration includes the `async` modifier then *return_type* for a restricted partial method shall be `void` or the method returns-by-value and the return type is a *task type* ([§15.14.1](classes.md#15141-general)). +The *return_type* of a returns-by-value or returns-no-value method declaration specifies the type of the result, if any, returned by the method. If the declaration includes the `async` modifier then *return_type* shall be `void` or the method returns-by-value and the return type is a *task type* ([§15.14.1](classes.md#15141-general)). The *ref_return_type* of a returns-by-ref method declaration specifies the type of the variable referenced by the *variable_reference* returned by the method. @@ -2389,7 +2389,7 @@ For a `struct` type, within an instance method, instance accessor ([§12.2.1](ex A parameter declared with an `out` modifier is an ***output parameter***. For definite-assignment rules, see [§9.2.7](variables.md#927-output-parameters). -A method declared as a restricted partial method ([§15.6.9](classes.md#1569-partial-methods)) shall not have output parameters. +A method declared as a restricted partial method (§restricted-partial-methods) shall not have output parameters. > *Note*: Output parameters are typically used in methods that produce multiple return values. *end note* @@ -3027,20 +3027,27 @@ The mechanism by which linkage to an external method is achieved is implementati ### 15.6.9 Partial methods +#### §partial-methods-general General + When a *method declaration* includes a `partial` modifier, that method is said to be a ***partial method***. Partial methods may only be declared as members of partial types ([§15.2.7](classes.md#1527-partial-type-declarations)). -Partial methods may be defined in one part of a type declaration and implemented in another, or be defined and implemented in the same part. +There are two versions of partial methods: restricted and unrestricted. A ***restricted partial method*** (§restricted-partial-methods) has no explicit access modifiers, and is implicitly private. An ***unrestricted partial method*** (§unrestricted-partial-methods) is a partial method that includes one or more explicit access modifiers. + +There are two kinds of partial method declarations: -There are two kinds of partial method declarations: If the body of the method declaration is a semicolon, the declaration is said to be a ***defining partial method declaration***. Otherwise, the declaration is said to be an ***implementing partial method declaration***. Across the parts of a type declaration, there may be only one defining partial method declaration with a given signature, and there may be only one implementing partial method declaration with a given signature. If an implementing partial method declaration is given, a corresponding defining partial method declaration shall exist, and the declarations shall match as specified in the following: +- A method with an *expression-body* or a *block-body* or is declared with the `extern` modifier is said to be an ***implementing partial method declaration***. +- Otherwise, a method declaration where the body of the method declaration is a semicolon is said to be a ***defining partial method declaration***. -- The declarations shall have the same modifiers (although not necessarily in the same order), with the exception of the `async` and `extern` modifiers which shall not appear on a defining part. -- In the case of private accessibility, both declarations shall be implicitly private (that is, with no accessibility modifier) or both shall be explicitly `private`. +Across the parts of a type declaration, there shall be exactly one defining partial method declaration with a given signature. For an implementing partial method declaration is given, a corresponding defining partial method declaration shall exist, and the declarations shall match as specified in the following: + +- The declarations shall have the same method name, number of type parameters, and number of parameters. +- The declarations shall have the same modifiers except for the `async` and `extern` modifiers. The `async` and `extern` modifiers are allowed only on the implementing partial method declaration. - Corresponding parameters in the declarations shall have the same modifiers (although not necessarily in the same order) and the same types (modulo differences in type parameter names). - Corresponding type parameters in the declarations shall have the same constraints (modulo differences in type parameter names). -Over time, the specification for partial methods has evolved, resulting in restricted and unrestricted versions. A ***restricted partial method*** has no explicit access modifiers (and is implicitly private), has a `void` return type, and has no out parameters. An ***unrestricted partial method*** is a partial method that has explicit access modifiers, a non-`void` return type, or any out parameters. +Partial methods may be defined in one part of a type declaration and implemented in another, or be defined and implemented in the same part. -For a restricted partial method, the implementation is optional; if no part implements the partial method, the partial method declaration and all calls to it are removed from the type declaration resulting from the combination of the parts. For an unrestricted partial method both the definition and implementation shall exist. +For an unrestricted partial method both the definition and implementation shall exist. In *method_declaration*, the identifier `partial` is recognized as a contextual keyword ([§6.4.4](lexical-structure.md#644-keywords)) only if it immediately precedes the *return_type*. A partial method cannot explicitly implement interface methods. @@ -3068,12 +3075,8 @@ In *method_declaration*, the identifier `partial` is recognized as a contextual > > *end example* -Only a defining partial method participates in overload resolution. As such, in the case of a restricted partial method, whether or not an implementing declaration is given, invocation expressions may resolve to invocations of the partial method. +Only a defining partial method participates in overload resolution. -> *Note*: Because a restricted partial method always returns `void`, such invocation expressions will always be expression statements. Furthermore, because a restricted partial method is implicitly `private`, such statements will always occur within one of the parts of the type declaration within which the partial method is declared. *end note* - - - > *Note*: The definition of matching defining and implementing partial method declarations does not require parameter names to match. This can produce *surprising*, albeit *well defined*, behaviour when named arguments ([§12.6.2.1](expressions.md#12621-general)) are used. For example, given the defining partial method declaration for `M` in one file, and the implementing partial method declaration in another file: > > @@ -3096,25 +3099,12 @@ Only a defining partial method participates in overload resolution. As such, in > > *end note* -If a restricted partial method has no implementation, any expression statement invoking it is simply removed from the combined type declaration. Thus, the invocation expression, including any subexpressions, has no effect at run-time. The partial method itself is also removed and will not be a member of the combined type declaration. - If an implementing declaration exists for a given partial method, the invocations of the partial methods are retained. The partial method gives rise to a method declaration similar to the implementing partial method declaration except for the following: -- The `partial` modifier is not included. - +- All modifiers except the `partial` modifier are combined, including any `extern` or `async` modifier declared on the implementing declaration. - The attributes in the resulting method declaration are the combined attributes of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. - - The attributes on the parameters of the resulting method declaration are the combined attributes of the corresponding parameters of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. - -If a defining declaration but not an implementing declaration is given for a restricted partial method `M`, the following restrictions apply: - -- It is a compile-time error to create a delegate from `M` ([§12.8.17.5](expressions.md#128175-delegate-creation-expressions)). - -- It is a compile-time error to refer to `M` inside an anonymous function that is converted to an expression tree type ([§8.6](types.md#86-expression-tree-types)). - -- Expressions occurring as part of an invocation of `M` do not affect the definite assignment state ([§9.4](variables.md#94-definite-assignment)), which can potentially lead to compile-time errors. - -- `M` cannot be the entry point for an application ([§7.1](basic-concepts.md#71-application-startup)). +- Any default arguments (§15.6.2) in the implementing declaration are removed. Partial methods are useful for allowing one part of a type declaration to customize the behavior of another part, e.g., one that is generated by a tool. Consider the following partial class declaration: @@ -3198,6 +3188,31 @@ class Customer } ``` +#### §restricted-partial-methods Restricted partial methods + +A restricted partial method shall have a `void` return type, and shall not declare out parameters. There shall be zero or one implementing declaration for each defining declaration. If no part implements the partial method, the partial method declaration and all calls to it are removed from the type declaration resulting from the combination of the parts. Whether or not an implementing declaration is given, invocation expressions may resolve to invocations of the partial method. + +The implementing member for a restricted partial method shall not be an external method (§15.6.8). + +> *Note*: Because a restricted partial method always returns `void`, such invocation expressions will always be expression statements. Furthermore, because a restricted partial method is implicitly `private`, such statements will always occur within one of the parts of the type declaration within which the partial method is declared. *end note* + +If a restricted partial method has no implementation, any expression statement invoking it is removed from the combined type declaration. Thus, the invocation expression, including any subexpressions, has no effect at run-time. The partial method itself is also removed and will not be a member of the combined type declaration. + +If a defining declaration but not an implementing declaration is given for a restricted partial method `M`, the following restrictions apply: + +- It is a compile-time error to create a delegate from `M` ([§12.8.17.5](expressions.md#128175-delegate-creation-expressions)). +- It is a compile-time error to refer to `M` inside an anonymous function that is converted to an expression tree type ([§8.6](types.md#86-expression-tree-types)). +- Expressions occurring as part of an invocation of `M` do not affect the definite assignment state ([§9.4](variables.md#94-definite-assignment)), which can potentially lead to compile-time errors. +- `M` cannot be the entry point for an application ([§7.1](basic-concepts.md#71-application-startup)). + +#### §unrestricted-partial-methods Unrestricted partial methods + +An unrestriced partial method has an explicit access modifier. There shall be exactly one implementing partial method declaration. + +The implementing declaration for an unrestricted partial method may be an external method (§15.6.8). + +> *Note:* The `private` access modifier is required on both the ***defining partial method declaration*** and the ***implementing partial method declaration*** of an unrestricted partial method. *end note* + ### 15.6.10 Extension methods When the first parameter of a method includes the `this` modifier, that method is said to be an ***extension method***. Extension methods shall only be declared in non-generic, non-nested static classes. The first parameter of an extension method is restricted, as follows: @@ -4265,7 +4280,7 @@ The *event_accessor_declarations* of an event specify the executable statements The accessor declarations consist of an *add_accessor_declaration* and a *remove_accessor_declaration*. Each accessor declaration consists of the token add or remove followed by a *block*. The *block* associated with an *add_accessor_declaration* specifies the statements to execute when an event handler is added, and the *block* associated with a *remove_accessor_declaration* specifies the statements to execute when an event handler is removed. -Each *add_accessor_declaration* and *remove_accessor_declaration* corresponds to a method with a single value parameter of the event type, and a `void` return type. The implicit parameter of an event accessor is named `value`. When an event is used in an event assignment, the appropriate event accessor is used. Specifically, if the assignment operator is `+=` then the add accessor is used, and if the assignment operator is `–=` then the remove accessor is used. In either case, the right operand of the assignment operator is used as the argument to the event accessor. The block of an *add_accessor_declaration* or a *remove_accessor_declaration* shall conform to the rules for `void` methods described in [§15.6.9](classes.md#1569-partial-methods). In particular, `return` statements in such a block are not permitted to specify an expression. +Each *add_accessor_declaration* and *remove_accessor_declaration* corresponds to a method with a single value parameter of the event type, and a `void` return type. The implicit parameter of an event accessor is named `value`. When an event is used in an event assignment, the appropriate event accessor is used. Specifically, if the assignment operator is `+=` then the add accessor is used, and if the assignment operator is `–=` then the remove accessor is used. In either case, the right operand of the assignment operator is used as the argument to the event accessor. The block of an *add_accessor_declaration* or a *remove_accessor_declaration* shall conform to the rules for `void` methods described in §restricted-partial-methods. In particular, `return` statements in such a block are not permitted to specify an expression. Since an event accessor implicitly has a parameter named `value`, it is a compile-time error for a local variable or constant declared in an event accessor to have that name. From 5839c046506771c03501671ab43f08c98ad32326 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Fri, 9 Jan 2026 11:27:22 -0500 Subject: [PATCH 03/10] Some final edits Clean up a bit of language and flow. --- standard/classes.md | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index a4da81a98..197dd177d 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -3029,11 +3029,11 @@ The mechanism by which linkage to an external method is achieved is implementati #### §partial-methods-general General -When a *method declaration* includes a `partial` modifier, that method is said to be a ***partial method***. Partial methods may only be declared as members of partial types ([§15.2.7](classes.md#1527-partial-type-declarations)). +When a *method declaration* includes a `partial` modifier, that method is said to be a ***partial method***. Partial methods may only be declared as members of partial types ([§15.2.7](classes.md#1527-partial-type-declarations)). Partial methods may be defined in one part of a type declaration and implemented in another. -There are two versions of partial methods: restricted and unrestricted. A ***restricted partial method*** (§restricted-partial-methods) has no explicit access modifiers, and is implicitly private. An ***unrestricted partial method*** (§unrestricted-partial-methods) is a partial method that includes one or more explicit access modifiers. +In *method_declaration*, the identifier `partial` is recognized as a contextual keyword ([§6.4.4](lexical-structure.md#644-keywords)) only if it immediately precedes the *return_type*. A partial method cannot explicitly implement interface methods. -There are two kinds of partial method declarations: +There are classifications of a partial method declaration: - A method with an *expression-body* or a *block-body* or is declared with the `extern` modifier is said to be an ***implementing partial method declaration***. - Otherwise, a method declaration where the body of the method declaration is a semicolon is said to be a ***defining partial method declaration***. @@ -3045,12 +3045,10 @@ Across the parts of a type declaration, there shall be exactly one defining part - Corresponding parameters in the declarations shall have the same modifiers (although not necessarily in the same order) and the same types (modulo differences in type parameter names). - Corresponding type parameters in the declarations shall have the same constraints (modulo differences in type parameter names). -Partial methods may be defined in one part of a type declaration and implemented in another, or be defined and implemented in the same part. +There are two versions of partial methods: restricted and unrestricted. A ***restricted partial method*** (§restricted-partial-methods) has no explicit access modifiers, and is implicitly private. An ***unrestricted partial method*** (§unrestricted-partial-methods) is a partial method that includes one or more explicit access modifiers. For an unrestricted partial method both the definition and implementation shall exist. -In *method_declaration*, the identifier `partial` is recognized as a contextual keyword ([§6.4.4](lexical-structure.md#644-keywords)) only if it immediately precedes the *return_type*. A partial method cannot explicitly implement interface methods. - > *Example*: > > @@ -3101,7 +3099,7 @@ Only a defining partial method participates in overload resolution. If an implementing declaration exists for a given partial method, the invocations of the partial methods are retained. The partial method gives rise to a method declaration similar to the implementing partial method declaration except for the following: -- All modifiers except the `partial` modifier are combined, including any `extern` or `async` modifier declared on the implementing declaration. +- All modifiers except the `partial` modifier are included in the resulting, including any `extern` or `async` modifier declared on the implementing declaration. - The attributes in the resulting method declaration are the combined attributes of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. - The attributes on the parameters of the resulting method declaration are the combined attributes of the corresponding parameters of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. - Any default arguments (§15.6.2) in the implementing declaration are removed. @@ -3207,11 +3205,11 @@ If a defining declaration but not an implementing declaration is given for a res #### §unrestricted-partial-methods Unrestricted partial methods -An unrestriced partial method has an explicit access modifier. There shall be exactly one implementing partial method declaration. +An unrestriced partial method declartion incluces an explicit access modifier. There shall be exactly one implementing partial method declaration. -The implementing declaration for an unrestricted partial method may be an external method (§15.6.8). +The implementing declaration for an unrestricted partial method may be an external method (§15.6.8). The `extern` modifier is modifer allowed on an implementing partial declaration. It shall not be present on a defining partial declaration. -> *Note:* The `private` access modifier is required on both the ***defining partial method declaration*** and the ***implementing partial method declaration*** of an unrestricted partial method. *end note* +> *Note:* The `private` access modifier is required on both the ***defining partial method declaration*** and the ***implementing partial method declaration*** of a private unrestricted partial method. *end note* ### 15.6.10 Extension methods From 2e5175aeac290959c53a86e4cfc5de7772f69526 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Thu, 29 Jan 2026 11:23:27 -0500 Subject: [PATCH 04/10] Apply suggestions from code review Co-authored-by: Jon Skeet --- standard/classes.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index 197dd177d..e026daf63 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -3033,12 +3033,12 @@ When a *method declaration* includes a `partial` modifier, that method is said t In *method_declaration*, the identifier `partial` is recognized as a contextual keyword ([§6.4.4](lexical-structure.md#644-keywords)) only if it immediately precedes the *return_type*. A partial method cannot explicitly implement interface methods. -There are classifications of a partial method declaration: +Partial method declarations are classified as follows: - A method with an *expression-body* or a *block-body* or is declared with the `extern` modifier is said to be an ***implementing partial method declaration***. - Otherwise, a method declaration where the body of the method declaration is a semicolon is said to be a ***defining partial method declaration***. -Across the parts of a type declaration, there shall be exactly one defining partial method declaration with a given signature. For an implementing partial method declaration is given, a corresponding defining partial method declaration shall exist, and the declarations shall match as specified in the following: +Across the parts of a type declaration, there shall be exactly one defining partial method declaration with a given signature. If an implementing partial method declaration is given, a corresponding defining partial method declaration shall exist, and the declarations shall match as specified in the following: - The declarations shall have the same method name, number of type parameters, and number of parameters. - The declarations shall have the same modifiers except for the `async` and `extern` modifiers. The `async` and `extern` modifiers are allowed only on the implementing partial method declaration. @@ -3099,7 +3099,7 @@ Only a defining partial method participates in overload resolution. If an implementing declaration exists for a given partial method, the invocations of the partial methods are retained. The partial method gives rise to a method declaration similar to the implementing partial method declaration except for the following: -- All modifiers except the `partial` modifier are included in the resulting, including any `extern` or `async` modifier declared on the implementing declaration. +- All modifiers except the `partial` modifier are included in the resulting method declaration, including any `extern` or `async` modifier declared on the implementing declaration. - The attributes in the resulting method declaration are the combined attributes of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. - The attributes on the parameters of the resulting method declaration are the combined attributes of the corresponding parameters of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. - Any default arguments (§15.6.2) in the implementing declaration are removed. @@ -3205,7 +3205,7 @@ If a defining declaration but not an implementing declaration is given for a res #### §unrestricted-partial-methods Unrestricted partial methods -An unrestriced partial method declartion incluces an explicit access modifier. There shall be exactly one implementing partial method declaration. +An unrestricted partial method declaration incluces an explicit access modifier. There shall be exactly one implementing partial method declaration. The implementing declaration for an unrestricted partial method may be an external method (§15.6.8). The `extern` modifier is modifer allowed on an implementing partial declaration. It shall not be present on a defining partial declaration. From 1e6882246c24c32f56f8a2c02cbbc0cda4ebcb35 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Thu, 29 Jan 2026 13:54:47 -0500 Subject: [PATCH 05/10] Respond to meeting feedback Investigate and respond to feedback from reviews. Implement the proposed name change to "optional" and "required" --- standard/classes.md | 42 +++++++++++++++++++++--------------------- 1 file changed, 21 insertions(+), 21 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index e026daf63..4558777ba 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -2152,7 +2152,7 @@ A declaration has a valid combination of modifiers if all of the following are t - If the declaration includes the `private` modifier, then the declaration does not include any of the following modifiers: `virtual`, `override`, or `abstract`. - If the declaration includes the `sealed` modifier, then the declaration also includes the `override` modifier. - If the declaration includes the `partial` modifier, then it does not include the modifier `abstract`. -- If the declaration is for a restricted partial method (§restricted-partial-methods), then it does not include any of the following modifiers: `new`, `public`, `protected`, `internal`, `private`, `virtual`, `sealed`, `override`, or `extern`. +- If the declaration is for a required partial method (§required-partial-methods), then it does not include any of the following modifiers: `new`, `public`, `protected`, `internal`, `private`, `virtual`, `sealed`, `override`, or `extern`. Methods are classified according to what, if anything, they return: @@ -2389,7 +2389,7 @@ For a `struct` type, within an instance method, instance accessor ([§12.2.1](ex A parameter declared with an `out` modifier is an ***output parameter***. For definite-assignment rules, see [§9.2.7](variables.md#927-output-parameters). -A method declared as a restricted partial method (§restricted-partial-methods) shall not have output parameters. +A method declared as a required partial method (§required-partial-methods) shall not have output parameters. > *Note*: Output parameters are typically used in methods that produce multiple return values. *end note* @@ -3042,12 +3042,12 @@ Across the parts of a type declaration, there shall be exactly one defining part - The declarations shall have the same method name, number of type parameters, and number of parameters. - The declarations shall have the same modifiers except for the `async` and `extern` modifiers. The `async` and `extern` modifiers are allowed only on the implementing partial method declaration. -- Corresponding parameters in the declarations shall have the same modifiers (although not necessarily in the same order) and the same types (modulo differences in type parameter names). -- Corresponding type parameters in the declarations shall have the same constraints (modulo differences in type parameter names). +- Corresponding parameters in the declarations shall have the same modifiers (although not necessarily in the same order) and the same types (modulo differences in type parameter names). Tuple types (§8.3.11) used as parameters or return types shall have the same item names in both the defining and implementing partial method declarations. +- Corresponding type parameters in the declarations shall have the same constraints. An implementation may choose to issue a warning if the type parameter names are different in the defining and implementing declarations. -There are two versions of partial methods: restricted and unrestricted. A ***restricted partial method*** (§restricted-partial-methods) has no explicit access modifiers, and is implicitly private. An ***unrestricted partial method*** (§unrestricted-partial-methods) is a partial method that includes one or more explicit access modifiers. +There are two classifications of partial methods: required and optional. A ***required partial method*** (§required-partial-methods) has no explicit access modifiers, and is implicitly private. An ***optional partial method*** (§optional-partial-methods) is a partial method that includes one or more explicit access modifiers. -For an unrestricted partial method both the definition and implementation shall exist. +For an optional partial method both the definition and implementation shall exist. > *Example*: > @@ -3056,10 +3056,10 @@ For an unrestricted partial method both the definition and implementation shall > // part containing defining partial method declarations > partial class C > { -> partial void M1(); // restricted, impl. optional -> private partial void M2(); // unrestricted, impl. required -> protected partial bool M3(); // unrestricted, impl. required -> public partial void M4(out int i); // unrestricted, impl. required +> partial void M1(); // implementation optional +> private partial void M2(); // required, impl. required +> protected partial bool M3(); // required, impl. required +> public partial void M4(out int i); // required, impl. required > } > > // part containing implementing partial method declarations @@ -3186,30 +3186,30 @@ class Customer } ``` -#### §restricted-partial-methods Restricted partial methods +#### §required-partial-methods Required partial methods -A restricted partial method shall have a `void` return type, and shall not declare out parameters. There shall be zero or one implementing declaration for each defining declaration. If no part implements the partial method, the partial method declaration and all calls to it are removed from the type declaration resulting from the combination of the parts. Whether or not an implementing declaration is given, invocation expressions may resolve to invocations of the partial method. +A required partial method shall have a `void` return type, and shall not declare out parameters. There shall be zero or one implementing declaration for each defining declaration. If no part implements the partial method, the partial method declaration and all calls to it are removed from the type declaration resulting from the combination of the parts. Whether or not an implementing declaration is given, invocation expressions may resolve to invocations of the partial method. -The implementing member for a restricted partial method shall not be an external method (§15.6.8). +The implementing member for a required partial method shall not be an external method (§15.6.8). -> *Note*: Because a restricted partial method always returns `void`, such invocation expressions will always be expression statements. Furthermore, because a restricted partial method is implicitly `private`, such statements will always occur within one of the parts of the type declaration within which the partial method is declared. *end note* +> *Note*: Because a required partial method always returns `void`, such invocation expressions will always be expression statements. Furthermore, because a required partial method is implicitly `private`, such statements will always occur within one of the parts of the type declaration within which the partial method is declared. *end note* -If a restricted partial method has no implementation, any expression statement invoking it is removed from the combined type declaration. Thus, the invocation expression, including any subexpressions, has no effect at run-time. The partial method itself is also removed and will not be a member of the combined type declaration. +If a required partial method has no implementation, any expression statement invoking it is removed from the combined type declaration. Thus, the invocation expression, including any subexpressions, has no effect at run-time. The partial method itself is also removed and will not be a member of the combined type declaration. -If a defining declaration but not an implementing declaration is given for a restricted partial method `M`, the following restrictions apply: +If a defining declaration but not an implementing declaration is given for a required partial method `M`, the following restrictions apply: - It is a compile-time error to create a delegate from `M` ([§12.8.17.5](expressions.md#128175-delegate-creation-expressions)). - It is a compile-time error to refer to `M` inside an anonymous function that is converted to an expression tree type ([§8.6](types.md#86-expression-tree-types)). - Expressions occurring as part of an invocation of `M` do not affect the definite assignment state ([§9.4](variables.md#94-definite-assignment)), which can potentially lead to compile-time errors. - `M` cannot be the entry point for an application ([§7.1](basic-concepts.md#71-application-startup)). -#### §unrestricted-partial-methods Unrestricted partial methods +#### optional-partial-methods Optional partial methods -An unrestricted partial method declaration incluces an explicit access modifier. There shall be exactly one implementing partial method declaration. +An optional partial method declaration incluces an explicit access modifier. There shall be exactly one implementing partial method declaration. -The implementing declaration for an unrestricted partial method may be an external method (§15.6.8). The `extern` modifier is modifer allowed on an implementing partial declaration. It shall not be present on a defining partial declaration. +The implementing declaration for an optional partial method may be an external method (§15.6.8). The `extern` modifier is modifer allowed on an implementing partial declaration. It shall not be present on a defining partial declaration. -> *Note:* The `private` access modifier is required on both the ***defining partial method declaration*** and the ***implementing partial method declaration*** of a private unrestricted partial method. *end note* +> *Note:* The `private` access modifier is required on both the ***defining partial method declaration*** and the ***implementing partial method declaration*** of a private optional partial method. *end note* ### 15.6.10 Extension methods @@ -4278,7 +4278,7 @@ The *event_accessor_declarations* of an event specify the executable statements The accessor declarations consist of an *add_accessor_declaration* and a *remove_accessor_declaration*. Each accessor declaration consists of the token add or remove followed by a *block*. The *block* associated with an *add_accessor_declaration* specifies the statements to execute when an event handler is added, and the *block* associated with a *remove_accessor_declaration* specifies the statements to execute when an event handler is removed. -Each *add_accessor_declaration* and *remove_accessor_declaration* corresponds to a method with a single value parameter of the event type, and a `void` return type. The implicit parameter of an event accessor is named `value`. When an event is used in an event assignment, the appropriate event accessor is used. Specifically, if the assignment operator is `+=` then the add accessor is used, and if the assignment operator is `–=` then the remove accessor is used. In either case, the right operand of the assignment operator is used as the argument to the event accessor. The block of an *add_accessor_declaration* or a *remove_accessor_declaration* shall conform to the rules for `void` methods described in §restricted-partial-methods. In particular, `return` statements in such a block are not permitted to specify an expression. +Each *add_accessor_declaration* and *remove_accessor_declaration* corresponds to a method with a single value parameter of the event type, and a `void` return type. The implicit parameter of an event accessor is named `value`. When an event is used in an event assignment, the appropriate event accessor is used. Specifically, if the assignment operator is `+=` then the add accessor is used, and if the assignment operator is `–=` then the remove accessor is used. In either case, the right operand of the assignment operator is used as the argument to the event accessor. The block of an *add_accessor_declaration* or a *remove_accessor_declaration* shall conform to the rules for `void` methods described in §required-partial-methods. In particular, `return` statements in such a block are not permitted to specify an expression. Since an event accessor implicitly has a parameter named `value`, it is a compile-time error for a local variable or constant declared in an event accessor to have that name. From 2a11484efc942f95ae6c27665c6239c66c33f6a1 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Thu, 29 Jan 2026 14:00:20 -0500 Subject: [PATCH 06/10] fix build issues --- standard/classes.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index 4558777ba..608b8d87b 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -3099,7 +3099,7 @@ Only a defining partial method participates in overload resolution. If an implementing declaration exists for a given partial method, the invocations of the partial methods are retained. The partial method gives rise to a method declaration similar to the implementing partial method declaration except for the following: -- All modifiers except the `partial` modifier are included in the resulting method declaration, including any `extern` or `async` modifier declared on the implementing declaration. +- The `partial` modifier is not included in the combined method declaration. - The attributes in the resulting method declaration are the combined attributes of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. - The attributes on the parameters of the resulting method declaration are the combined attributes of the corresponding parameters of the defining and the implementing partial method declaration in unspecified order. Duplicates are not removed. - Any default arguments (§15.6.2) in the implementing declaration are removed. @@ -3203,7 +3203,7 @@ If a defining declaration but not an implementing declaration is given for a req - Expressions occurring as part of an invocation of `M` do not affect the definite assignment state ([§9.4](variables.md#94-definite-assignment)), which can potentially lead to compile-time errors. - `M` cannot be the entry point for an application ([§7.1](basic-concepts.md#71-application-startup)). -#### optional-partial-methods Optional partial methods +#### §optional-partial-methods Optional partial methods An optional partial method declaration incluces an explicit access modifier. There shall be exactly one implementing partial method declaration. From 85d860ebf032848cb7b5335e9edafea252dcd8b3 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Wed, 25 Feb 2026 13:54:42 -0500 Subject: [PATCH 07/10] Apply suggestions from code review Co-authored-by: Jon Skeet --- standard/classes.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index 608b8d87b..88b821a11 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -2160,7 +2160,7 @@ Methods are classified according to what, if anything, they return: - Otherwise, if *return_type* is `void`, the method is ***returns-no-value*** and does not return a value; - Otherwise, the method is ***returns-by-value*** and returns a value. -The *return_type* of a returns-by-value or returns-no-value method declaration specifies the type of the result, if any, returned by the method. If the declaration includes the `async` modifier then *return_type* shall be `void` or the method returns-by-value and the return type is a *task type* ([§15.14.1](classes.md#15141-general)). +The *return_type* of a returns-by-value or returns-no-value method declaration specifies the type of the result, if any, returned by the method. If the declaration includes the `async` modifier then *return_type* shall be `void` or the method returns-by-value and the return type shall be a *task type* ([§15.14.1](classes.md#15141-general)). The *ref_return_type* of a returns-by-ref method declaration specifies the type of the variable referenced by the *variable_reference* returned by the method. @@ -3047,7 +3047,7 @@ Across the parts of a type declaration, there shall be exactly one defining part There are two classifications of partial methods: required and optional. A ***required partial method*** (§required-partial-methods) has no explicit access modifiers, and is implicitly private. An ***optional partial method*** (§optional-partial-methods) is a partial method that includes one or more explicit access modifiers. -For an optional partial method both the definition and implementation shall exist. +For a required partial method both the definition and implementation shall exist. > *Example*: > From 5f9ccc3d032f6e7e67ad23f0c35e44fbf1dede34 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Wed, 25 Feb 2026 14:03:24 -0500 Subject: [PATCH 08/10] Respond to feedback. --- standard/classes.md | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index 88b821a11..9b91d644f 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -3045,7 +3045,7 @@ Across the parts of a type declaration, there shall be exactly one defining part - Corresponding parameters in the declarations shall have the same modifiers (although not necessarily in the same order) and the same types (modulo differences in type parameter names). Tuple types (§8.3.11) used as parameters or return types shall have the same item names in both the defining and implementing partial method declarations. - Corresponding type parameters in the declarations shall have the same constraints. An implementation may choose to issue a warning if the type parameter names are different in the defining and implementing declarations. -There are two classifications of partial methods: required and optional. A ***required partial method*** (§required-partial-methods) has no explicit access modifiers, and is implicitly private. An ***optional partial method*** (§optional-partial-methods) is a partial method that includes one or more explicit access modifiers. +There are two variations of partial methods: required and optional. A ***required partial method*** (§required-partial-methods) is a partial method that includes one or more explicit access modifiers. An ***optional partial method*** (§optional-partial-methods) has no explicit access modifiers, and is implicitly private. For a required partial method both the definition and implementation shall exist. @@ -3186,30 +3186,30 @@ class Customer } ``` -#### §required-partial-methods Required partial methods +#### §optional-partial-methods Optional partial methods -A required partial method shall have a `void` return type, and shall not declare out parameters. There shall be zero or one implementing declaration for each defining declaration. If no part implements the partial method, the partial method declaration and all calls to it are removed from the type declaration resulting from the combination of the parts. Whether or not an implementing declaration is given, invocation expressions may resolve to invocations of the partial method. +An optional partial method shall have a `void` return type, and shall not declare out parameters. There shall be zero or one implementing declaration for each defining declaration. If no part implements the partial method, the partial method declaration and all calls to it are removed from the type declaration resulting from the combination of the parts. Whether or not an implementing declaration is given, invocation expressions may resolve to invocations of the partial method. -The implementing member for a required partial method shall not be an external method (§15.6.8). +The implementing member for an optional partial method shall not be an external method (§15.6.8). -> *Note*: Because a required partial method always returns `void`, such invocation expressions will always be expression statements. Furthermore, because a required partial method is implicitly `private`, such statements will always occur within one of the parts of the type declaration within which the partial method is declared. *end note* +> *Note*: Because an optional partial method always returns `void`, such invocation expressions will always be expression statements. Furthermore, because an optional partial method is implicitly `private`, such statements will always occur within one of the parts of the type declaration within which the partial method is declared. *end note* -If a required partial method has no implementation, any expression statement invoking it is removed from the combined type declaration. Thus, the invocation expression, including any subexpressions, has no effect at run-time. The partial method itself is also removed and will not be a member of the combined type declaration. +If an optional partial method has no implementation, any expression statement invoking it is removed from the combined type declaration. Thus, the invocation expression, including any subexpressions, has no effect at run-time. The partial method itself is also removed and will not be a member of the combined type declaration. -If a defining declaration but not an implementing declaration is given for a required partial method `M`, the following restrictions apply: +If a defining declaration but not an implementing declaration is given for an optional partial method `M`, the following restrictions apply: - It is a compile-time error to create a delegate from `M` ([§12.8.17.5](expressions.md#128175-delegate-creation-expressions)). - It is a compile-time error to refer to `M` inside an anonymous function that is converted to an expression tree type ([§8.6](types.md#86-expression-tree-types)). - Expressions occurring as part of an invocation of `M` do not affect the definite assignment state ([§9.4](variables.md#94-definite-assignment)), which can potentially lead to compile-time errors. - `M` cannot be the entry point for an application ([§7.1](basic-concepts.md#71-application-startup)). -#### §optional-partial-methods Optional partial methods +#### §required-partial-methods Required partial methods -An optional partial method declaration incluces an explicit access modifier. There shall be exactly one implementing partial method declaration. +An required partial method declaration includes an explicit access modifier. There shall be exactly one implementing partial method declaration. -The implementing declaration for an optional partial method may be an external method (§15.6.8). The `extern` modifier is modifer allowed on an implementing partial declaration. It shall not be present on a defining partial declaration. +The implementing declaration for a required partial method may be an external method (§15.6.8). The `extern` modifier is modifier allowed on an implementing partial declaration. It shall not be present on a defining partial declaration. -> *Note:* The `private` access modifier is required on both the ***defining partial method declaration*** and the ***implementing partial method declaration*** of a private optional partial method. *end note* +> *Note:* The `private` access modifier is required on both the ***defining partial method declaration*** and the ***implementing partial method declaration*** of a private required partial method. *end note* ### 15.6.10 Extension methods From 4f0e0e3a4c2e4cd47a882258cab87278c7c68bd3 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Wed, 25 Feb 2026 14:52:49 -0500 Subject: [PATCH 09/10] missed a couple... --- standard/classes.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index 9b91d644f..8cea4e214 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -2152,7 +2152,7 @@ A declaration has a valid combination of modifiers if all of the following are t - If the declaration includes the `private` modifier, then the declaration does not include any of the following modifiers: `virtual`, `override`, or `abstract`. - If the declaration includes the `sealed` modifier, then the declaration also includes the `override` modifier. - If the declaration includes the `partial` modifier, then it does not include the modifier `abstract`. -- If the declaration is for a required partial method (§required-partial-methods), then it does not include any of the following modifiers: `new`, `public`, `protected`, `internal`, `private`, `virtual`, `sealed`, `override`, or `extern`. +- If the declaration is for an optional partial method (§optional-partial-methods), then it does not include any of the following modifiers: `new`, `public`, `protected`, `internal`, `private`, `virtual`, `sealed`, `override`, or `extern`. Methods are classified according to what, if anything, they return: @@ -2389,7 +2389,7 @@ For a `struct` type, within an instance method, instance accessor ([§12.2.1](ex A parameter declared with an `out` modifier is an ***output parameter***. For definite-assignment rules, see [§9.2.7](variables.md#927-output-parameters). -A method declared as a required partial method (§required-partial-methods) shall not have output parameters. +A method declared as an optional partial method (§optional-partial-methods) shall not have output parameters. > *Note*: Output parameters are typically used in methods that produce multiple return values. *end note* From fbe81a531297865a00cf30264c5074261a3ded86 Mon Sep 17 00:00:00 2001 From: Bill Wagner Date: Wed, 25 Feb 2026 15:00:55 -0500 Subject: [PATCH 10/10] review and edit. --- standard/classes.md | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/standard/classes.md b/standard/classes.md index 8cea4e214..bed8e99fc 100644 --- a/standard/classes.md +++ b/standard/classes.md @@ -2184,7 +2184,7 @@ If the *method_body* consists of a semicolon, the declaration shall not include The *ref_method_body* of a returns-by-ref method is either a semicolon, a block body or an expression body. A block body consists of a *block*, which specifies the statements to execute when the method is invoked. An expression body consists of `=>`, followed by `ref`, a *variable_reference*, and a semicolon, and denotes a single *variable_reference* to evaluate when the method is invoked. -For abstract and extern methods, the *ref_method_body* consists simply of a semicolon; for all other methods, the *ref_method_body* is either a block body or an expression body. +For abstract and extern methods, the *ref_method_body* consists simply of a semicolon. For partial methods the *ref_method_body* may consist of either a semicolon, a block body or an expression body. For all other methods, the *ref_method_body* is either a block body or an expression body. The name, the number of type parameters, and the parameter list of a method define the signature ([§7.6](basic-concepts.md#76-signatures-and-overloading)) of the method. Specifically, the signature of a method consists of its name, the number of its type parameters, and the number, *parameter_mode_modifier*s ([§15.6.2.1](classes.md#15621-general)), and types of its parameters. The return type is not part of a method’s signature, nor are the names of the parameters, the names of the type parameters, or the constraints. When a parameter type references a type parameter of the method, the ordinal position of the type parameter (not the name of the type parameter) is used for type equivalence. @@ -3205,9 +3205,9 @@ If a defining declaration but not an implementing declaration is given for an op #### §required-partial-methods Required partial methods -An required partial method declaration includes an explicit access modifier. There shall be exactly one implementing partial method declaration. +A required partial method declaration includes an explicit access modifier. There shall be exactly one implementing partial method declaration. -The implementing declaration for a required partial method may be an external method (§15.6.8). The `extern` modifier is modifier allowed on an implementing partial declaration. It shall not be present on a defining partial declaration. +The implementing declaration for a required partial method may be an external method (§15.6.8). The `extern` modifier is allowed on an implementing partial declaration. It shall not be present on a defining partial declaration. > *Note:* The `private` access modifier is required on both the ***defining partial method declaration*** and the ***implementing partial method declaration*** of a private required partial method. *end note* @@ -4278,7 +4278,7 @@ The *event_accessor_declarations* of an event specify the executable statements The accessor declarations consist of an *add_accessor_declaration* and a *remove_accessor_declaration*. Each accessor declaration consists of the token add or remove followed by a *block*. The *block* associated with an *add_accessor_declaration* specifies the statements to execute when an event handler is added, and the *block* associated with a *remove_accessor_declaration* specifies the statements to execute when an event handler is removed. -Each *add_accessor_declaration* and *remove_accessor_declaration* corresponds to a method with a single value parameter of the event type, and a `void` return type. The implicit parameter of an event accessor is named `value`. When an event is used in an event assignment, the appropriate event accessor is used. Specifically, if the assignment operator is `+=` then the add accessor is used, and if the assignment operator is `–=` then the remove accessor is used. In either case, the right operand of the assignment operator is used as the argument to the event accessor. The block of an *add_accessor_declaration* or a *remove_accessor_declaration* shall conform to the rules for `void` methods described in §required-partial-methods. In particular, `return` statements in such a block are not permitted to specify an expression. +Each *add_accessor_declaration* and *remove_accessor_declaration* corresponds to a method with a single value parameter of the event type, and a `void` return type. The implicit parameter of an event accessor is named `value`. When an event is used in an event assignment, the appropriate event accessor is used. Specifically, if the assignment operator is `+=` then the add accessor is used, and if the assignment operator is `–=` then the remove accessor is used. In either case, the right operand of the assignment operator is used as the argument to the event accessor. The block of an *add_accessor_declaration* or a *remove_accessor_declaration* shall conform to the rules for `void` methods described in [§15.6.11](classes.md#15611-method-body). In particular, `return` statements in such a block are not permitted to specify an expression. Since an event accessor implicitly has a parameter named `value`, it is a compile-time error for a local variable or constant declared in an event accessor to have that name.