Activating my extension only in certain markdown files

[ejgallego]

Dear VSCode community,

summary: we'd like our extension to activate only on markdown files with extension .mv

we have an extension (https://github.com/ejgallego/coq-lsp) for the Coq Interactive Theorem prover. This extension opens a side panel showing proof information files as it is customary in the Coq / Interactive Theorem Proving community.

Our extension also supports literate markdown documents, that is to say, markdown documents with embedded Coq code snippets marked with coq blocks.

Ideally, we'd like our extension to only activate for markdown files that have the .mv extension, as we think it'd be intrusive for our extension to activate on all markdown files, due to the right side panel. We'd also like for the primary type of our .mv files to stay as Markdown, as it makes sense due to preview, etc...

However, we are struggling having our extension to activate automatically when a .mv file is opened. As of now, if we open an .mv file, the extension won't activate. Once the extension is activated by other means, it works fine with the .mv files.

This is our contribution point:

  "contributes": {
    "languages": [
      {
        "id": "markdown",
        "aliases": [
          "Markdown"
        ],
        "extensions": [
          ".mv"
        ]
      }
    ]

Is it possible for us to do what we want?

TIA!

[Ninglo]

First, we can set up the extension activation event:

"activationEvents": [
    "workspaceContains:**/*.mv"
]

After the extension is activated, we can observe workspace event changes (for example: onDidOpenTextDocument) and we can perform real logic when the user opens a specific file.

export function activate() {
  vscode.workspace.onDidOpenTextDocument((textDocument) => {
    if (
      textDocument.languageId === "markdown" &&
      textDocument.name.endsWith(".mv")
    ) {
      // Do something
    }
  });
}

Note that these codes have not been actually tested, so some content may not be completely accurate and are for reference only.

Hope this helps you.

[Ninglo]

One thing to add is that you don't need to execute all the logic when activating the plugin. You can just listen for events and respond when relevant events occur.

[alefragnani]

Hi @ejgallego ,

There is no single activationEvent setting to achieve what you want, but you still can use take advantage of the regular Markdown features (like the Preview you mentioned), if you add this simple setting:

    "files.associations": {
        "*.mv": "markdown"
    },

Using files.associations setting, whenever you open a .mv file, it will be recognized as markdown.

I'm not entirely sure, but I guess that this may work even if your .mv file is defined as a new language. Sure, this would require your extension to update the user settings somehow (a command, instructions in readme, step in walkthrough) but it is doable, Worth a try 😬

Hope this helps

[theReynald]

Hi @ejgallego,

Does the follow responses help?

[ejgallego]

Hi all! Thanks a lot for all the amazing answers and help, I will look into them this upcomign week, I was offline for the past week.

Something that has me wondering is that maybe there could be a bug in the new activation code.

With the current code, when I activate the extension manually, it is properly activated on all the .mv files, so what it fails is the auto-activation, but I don't see how this should be the case.

I'll test and report back soon, thanks for your patience.

[r3m0t]

Hi, I think onLanguage:markdown would be a better event for you. Also, once activated make sure to loop through all open editors for mv files. For example if the user restores a window from the last time they had VS Code open, the events may not fire or may have fired before your extension activated.

[ejgallego]

Hi folks, thanks again for all the help, but the more I think about this, the more it seems a bug (likely due to the new activation setup in 1.74).

It makes little sense to me that the following happens as of now:

• when the extension was not activated, .mv files are not recognized
• however when the extension was activated by other means, the extension is correctly active for old and new .mv files.

Isn't that strange? Dunno if I should file a bug.

Hi, I think onLanguage:markdown would be a better event for you. Also, once activated make sure to loop through all open editors for mv files. For example if the user restores a window from the last time they had VS Code open, the events may not fire or may have fired before your extension activated.

Adding onLanguage:markdown plus my current contributes code makes things work as I want, thanks!

That would be a solution, however I am not sure this is not a bug; I'd like to determine if that looks like a bug before closing the question.

What do you mean by "the events may not fire or may have fired before your extension activated" ?

I'd like to add a test case for this, but I wasn't able to reproduce this behavior so I cannot test the code that would iterate the docs.

Note that my extension is a LSP client one, so once activated the LSP client takes care of synching the editor, etc...

[isidorn]

Might be best to file a bug here https://github.com/microsoft/vscode
And someone from the dev team should be able to help. Thank you

[ejgallego]

Thanks a lot @isidorn, indeed I think I have collected enough evidence to warrant bothering the devs with this. Thanks again to everyone!