How to prompt installation of additional python packages from another extension?

[ssbarnea]

I am trying to enable few additional python based linters for another extension but I was not able to find how can I reuse vscode-python functionality for prompting and installing the missing tools.

Is there any example of another extension that makes use of vscode-python code in order to trigger installation fo other python packages?

I do have at least 3 other tools in mind: doc8, ansible-lint or pre-commit to the list of linters from this project but none of these target python code itself, they are all python based. I seen the current implementation and is quite complex, for genuine reasons as there are many ways to install python and packages.

If someone can point to an example where this was sorted it would be great. At this stage I only detect that the tool is missing, and tell the user to find a way to install it, which can be confusing for some of them.

[brettcannon]

I'm not aware of any other extension that has explicitly copied that bit of code from us. Are you just wanting a pointer in our own code of where we handle this? Basically we just try to run the linter with python -m <linter> and if it fails we say it isn't installed.

[ssbarnea]

I have no complaints about how you check for current linters, my only issue is that I cannot reuse vscode-python to add new linters via another extension. Copying the code that takes care of detection, prompting and installing is not practical at all as it deeply embedded into the extension itself.

If you would not mind, I would like to suggest allowing other extensions to extend the default list of linters using a contribution point -- for example extensions can contribute extra schemas support, so the user does not have to edit his settings.json to add extra patterns for matching different schemas.

For example an extension author should be able to write something like this into its extension package.json:

"contributes": {
    "configuration": {
        "python.tools": [{
           "name": "foo",
           "command": "python -m foo",
           "dependencies": "foo[some-extra] bar"
    }]
}

If implemented this would allow others to write vscode extensions that make use of python tools where installation of dependencies is taking care by the vscode-python itself. This makes a lot of sense as this extension determines which python interpreter is used by the project.

I do not expect vscode-python itself to run these tools (linters), but only to assist with their installation using pip. It would be up to extension developers to make use of those later. Main reason for this is because I expect we do not want to clutter main python extension with features that may prove to be less mainstream, especially due to maintenance concerns.

[brettcannon]

We are having some conversations on the team right now on ways to make it easy for people to create their own linter extensions, so I don't expect we will end up wanting to open up an contribution point like this and instead push people to create their own extension instead.