Allow plugins to bail out of custom message and do it themselfs with substitutions

[AndyOGo]

What is the problem you're trying to solve?

My plugin provides a custom message with substituted interpolations.
Unfortunately they are overruled by stylelint's message option introduced with #672

Support for substitutions has never been added and the request for it got closed #836

Seem that it is ignored because of this general solution, so I deleted the customMessages entry for my rule, like:

delete result.stylelint.customMessages[ruleName];

What solution would you like to see?

Well, some official way of saying, hey stylelint this plugin is handling the message option by itself.

Original issue in my plugin: AndyOGo/stylelint-declaration-strict-value#142

[jeddy3]

@AndyOGo Thanks for the request.

Labelling as a discussion for now. Ideally, we would provide a common way for using interpolated values in custom messages that all plugins can use, but in the meantime, an official flag may by the best option.

Support for substitutions has never been added and the request for it got closed #836

It picked up again in #4117, but the issue has stalled.

[SalimBensiali]

I would love the ability to supplement the default message with extra info and recommendation. We have RTL aware Sass variables that we want developers to use instead of margin-left, border-left-color etc. And a custom message currently lacks the ability to preserve the existing message. Something with string interpolation or an additional_message option would be grand.

I would love to be able to do the following for example

{
  "rules": {
    "property-disallowed-list": [
      "/left|right$/",
      {
        "message": "${original_message}. Use the \"$start-direction\" & \"$end-direction\" SASS variables instead of \"left\" & \"right\".",
      }
    ]
  }
}

or

{
  "rules": {
    "property-disallowed-list": [
      "/left|right$/",
      {
        "additional_message": "Use the \"$start-direction\" & \"$end-direction\" SASS variables instead of \"left\" & \"right\".",
      }
    ]
  }
}

[SalimBensiali]

@jeddy3 Is there anything I can help with on this one? I would be keen to contribute, or is this needing internal discussion first?

Thanks.

[jeddy3]

@SalimBensiali Thanks for offering to contribute. The original interpolated custom messages issue (#4117) stalled, but a proof-of-concept pull request showing how this might work would be a good start in getting it going again. It is probably worth seeing if this problem has been solved in other tools, and applying their approach here in stylelint.

[SalimBensiali]

Thanks @jeddy3. I will do some research and raise a POC PR afterwards.

[Mouvedia]

@ybiquitous is this achievable since #6312 merge?

[ybiquitous]

Yes, let's close this. The functional message support should resolve this issue.

stylelint/docs/user-guide/configure.md

Lines 150 to 160 in 68cb920

	Experimental feature: some rules support message arguments. For example, when configuring the `color-no-hex` rule, the hex color can be used in the message string:
	`.stylelintrc.js`:
	```js
	{
	'color-no-hex': [true, {
	message: (hex) => `Don't use hex colors like "${hex}"`,
	}]
	}
	```