Make it clear what happens when multiple formatters for one document apply

[octref]

• VSCode Version: 1.19
• OS Version: macOS 1.12.6

Recently prettier added partial Vue support, and prettier-vscode starts to register itself as a Vue formatter. When user presses format, prettier-vscode was being used (instead of the formatter in Vetur).

vuejs/vetur#658

The user should be given the choice to select a formatter for a specific language.

[jrieken]

The user should be given the choice to select a formatter for a specific language.

How? A formatter has no name nor any other means of identification. We can use the extension name/id but that would only work if there is just one. Worst, the choice cannot be remembered because a formatter is registered with a document selector and (in theory) every document (even of the same language*) can be formatted by a different formatter.

We have always recommended extensions to either ship more fine-grained, e.g. have a separate formatter extension (and let the user decide by installing/uninstalling) or to add an option to enable/disable their formatter (more commonly used).

*) A sample is remote/live edit scenarios in which your extension host knows TypeScript files on your disk (file-scheme) and other TypeScript files from somewhere else, e.g. remote-scheme which are formatted by another entity, e.g. not the TS extension

[octref]

prettier-vscode did add a config prettier.disableLanguages so this can be worked around. So I guess it's each extension's responsibility to make sure they don't clash with others.

However I still think there should be some visual indication when multiple formatters are being run on the same file. Now the order they are being run seem to be random and users thought the formatters are having bugs.

I feel no one would want multiple formatters being run on the same file, with order they can't control.

[jrieken]

I feel no one would want multiple formatters being run on the same file,

We don't run multiple formatters. We pick one and use that. It's just hard to pick one, esp when formatting happens from more subtle gestures like format on paste etc

[octref]

OK, running multiple formatter was a misunderstanding, but user not knowing which formatter getting picked isn't that good either.

If the choice of formatter can't be given to users via a setting easily, how about showing a message like "Multiple formatter is available for this document. VS Code defaults to use xxx formatter. Please update your formatter setting if you would like to choose an alternative formatter"?

[jrieken]

VS Code defaults to use xxx formatter.

Problem is the xxx because when an extension registers multiple formatters that are only available under certain condition... It's an uncommon scenario not something we should keep in mind

[amatiasq]

Not sure if this is the place for this question but can't we run formatters sequentially?

[jrieken]

Interesting idea A. Matías Quezada (@amatiasq)... Sequentially maybe but without restart because otherwise you might format endlessly.

[usernamehw]

How about at least adding a way to get the current formatter(extension name - the one that will be used when you execute Format Document) ?