Pyright in a web worker requires refactor

[nchen63]

I have Pyright working in a web worker, but it required a few changes because there are dependencies on node. Would you be open to refactoring the code to abstract out the node dependencies? I could take a shot at a PR if you're ok with that.

[erictraut]

Can you summarize the changes here? The pylance team already has pyright running in a web browser, so I'm surprised to hear that additional refactoring was required to make this work.

[erictraut]

worker_threads is used only if background analysis is enabled. That can be disabled by creating a subclass of LanguageServerBase that overrides createBackgroundAnalysis to return undefined.

All of the file system calls are handled through an abstract file system interface that can be swapped out for another implementation. So that should require no refactoring — just an implementation of the file system interface that works within a web browser.

That just leaves the global object process. That can be easily shimmed by adding a global object that provides dummy implementations of the few methods and varaibles used by pyright: memoryUsage and execArgv.

So I think it should be straightforward to run pyright in a web browser without any further refactoring or abstractions.

[nchen63]

Clearly, it's possible to do these things as workarounds, but needing to shim and use global variables isn't a great experience for a module, and a hard sell for larger projects.

The change can be as simple as adding a single level of indirection for these dependencies.

[erictraut]

All of these are single levels of indirection. We're not interested in adding yet another level of indirection.

[erictraut]

The file system and background analysis abstractions are already overridable through well-designed mechanisms. The shim for process is admittedly not as clean. We could add a formal abstraction here, but I don't think it's worth it. A shim for process involves about five lines of code.

[wch]

I've made a version of pyright where it works completely in the browser, at https://github.com/posit-dev/pyright. It was originally based on this fork by micro:bit but is now substantially different.

I mostly followed @erictraut's advice, except that I was able to enable background analysis by making a shim for node:worker_threads, which is implemented using Web Workers.

For more information, see https://github.com/posit-dev/pyright/blob/pyright-browser/THIS_FORK.md

[FrankFang]

The pylance team already has pyright running in a web browser

Is there a demo or link?

[rchiodo]

You can use it at https://vscode.dev if you install the Pylance extension.