Prefactor some parts to reduce size of other PR

[ianjosephwilson]

• new modules
  • start preparing for more html spec constants by creating new module: htmlspec.py
  • move html dunder protocol into a module so we can more easily share it: protocols.py
  • Add sentinel for use in the project (until Python standardizes one, in 3.15? maybe): sentinel.py
• TemplateRef additions
  • add helper method for TemplateRef that iterates parts, omitting empty strings, like Template.__iter__ does.
  • add helper method to TemplateRef that resolves the interpolation values from a paired Template object in between the TemplateRef strings based on the i_indexes.
• new feature: "callback" format_spec triggers new formatter
  • Add callback formatter that executes a zero-arg callable before resolving the template values. This would be opt-in instead of any Callable passed into the Template being called automatically.

[davepeck]

This seems like a good pre-factor. But I'm a little unclear on where we're heading with component invocation?

[davepeck]

Interesting. How should I think about :callback?

Our dataclass-style components historically depend on tdom always calling callables if it finds them in content position. Has this also changed?

[ianjosephwilson]

Maybe: "call back to this function to get the effective value to plug into this interpolation whenever you end up processing this template". It is general purpose but by making it opt-in we don't have to check every single interpolation value to see if it is a callable or not.

Since this is a mixed bag of changes that were more easily extractable it might seem a little out of place but the other PR removes processing callables automatically and you HAVE to opt-in except for components which are their own flow.

Instead of going back out to start all over again ...

tdom/tdom/processor.py

Line 505 in f210a36

return _node_from_value(result)

... if the component callable is a factory then it is just immediately called a second time to get the Template.

https://github.com/t-strings/tdom/pull/105/changes#diff-4045942bbefd0bbd3a5a7e792e3dc8a234c7a9cfb0a7c136d38ce00fdfedd8c3R203

So instead of running everything through the same node_from_value function we have more dedicated flows that resolve values with more context.

[davepeck]

if the component callable is a factory then it is just immediately called a second time to get the Template

Ah, that makes sense. That's a better approach. Basically, a "component" can return a Template or a (zero-arg) callable. Fine.

[davepeck]

@ianjosephwilson This feels mergable. Agreed?

[ianjosephwilson]

Yes, should be just rearranging things and adding things, I don't think anything really changes.

[davepeck]

Thank you thank you!