Offer ability to short circuit help output (Ex: -h)

[Boscop]

Currently, passing -h doesn't work:

Unrecognized argument: -h

Passing -h should work the same as --help, unless one of the options/switches uses short = 'h'.

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And in the Usage output, it would then show

-h, --help display usage information

instead of just

--help display usage information

[Boscop]

Alternatively, to let the programmer decide (because maybe they want to use -h for something else),
there should be a way to manually call the function that prints the usage information (that's called when --help is passed).
So that it can be manually called when -h is passed with an explicit #[argh(switch, short = 'h')] help: bool field.

I.e. this function:

argh/argh_derive/src/help.rs

Line 22 in c752b5f

pub(crate) fn help(

But wrapped in a nicer way, callable as a method on the struct that FromArgs is derived on.

[benbrittain]

I'd be far more amicable to that change! That seems like a good option for those that want -h support

[msrd0]

I'd also like to see an -h shorthand flag, and I'd be willing to create a PR. However, I am concerned that letting the user implement the shorthand and argh worry about the long flag, the help would end up looking something like that:

Options:
  -h                display usage information
  --help            display usage information

Therefore, I think either the user should be given the option to specify a shorthand for the help message, or be able to "replace" the help switch altogether. Let me know what you think.

[benbrittain]

oh interesting, yes that makes sense. I'm open to a change like that!

[icefoxen]

Agreed on the -h shorthand flag. As for anything else, I don't want programmers to decide that -h should mean anything else, I want it to just be always a shorthand for --help.

[aminya]

I made a pull request that fixes this issue #106