Puro unexpectedly modifies PUB_CACHE env variable globally

[DanTup]

I was surprised to see paths in C:\Users\danny\.puro\shared\pub_cache showing up in projects where I had not used Puro. It appears that during installation, the PUB_CACHE env variable is changed globally.

This was rather unexpected to me - I don't think tools like this should modify variables that affect projects that aren't using them. It's also unclear to me why Puro can't just use the cache at the default location.

[pingbird]

The reason this was added is because there's unfortunately no other mechanism to tell pub which cache directory to use, particularly when invoked from an IDE (the IntelliJ / vscode plugins bypass the flutter/dart scripts and use the dart sdk directly). Perhaps a mistake in hindsight because it didn't end up fixing issues with pub global activate not being aware of which version of dart they were compiled with, a difficult problem to fix without replacing dart executables in the cache with a custom shim.

[DanTup]

the IntelliJ / vscode plugins bypass the flutter/dart scripts and use the dart sdk directly

For VS Code, I think Puro is already writing a .vscode/settings.json with the SDK path in? If so, it could write dart.env to set the PUB_CACHE for that project too.

If it has to be set globally, it could at least make it clear during installation. I was using Puro just to try to reproduce some bugs and I was surprised to find I had a second Pub Cache (and now I'm using a Windows Dev Drive for better performance, this change would actually move my cache back onto a non-Dev Drive and undo my performance gains).

(that said, it's still not clear to me what moving the folder gains at all.. if it's still a single fixed folder for SDKs, how does the custom location differ from the default?)

[pingbird]

I will be reverting this in the next release, new installs will use the default pub cache

[feinstein]

@pingbird so how active installs should proceed?