FEATURE REQUEST: Support for variable substitution when defining environment variables

[jeffkeller-einc]

It would be great if we could define environment variables as a function of other variables. VS Code seems to support this, though I haven't used it enough to know its limitations and intended uses.

For example:

HOSTNAME="www.example.com"
SERVICE_URI="https://${env:HOSTNAME}/path/to/endpoint"

or

SUPER_IMPORTANT_DIR="${env:HOME}/path/to/dir"

I would want to be able to set workspace environment variables that reference user and system environment variables.

[samclark2015]

Hey @jeffkeller-einc! Great to see you're using the environment variables feature.

I gave this a test myself, and found that system environment variables defined outside of Positron work as you'd hope. For example, SUPER_IMPORTANT_DIR="${env:HOME}/path/to/dir" resolves to /Users/me/path/to/dir.

However, I do also see that variables defined in Positron don't resolve this way. So, your SERVICE_URI example doesn't work.

It sounds like that latter case would be really useful, and I can create an issue from this feature request to get the idea working its way into Positron. What are your thoughts, given the ability to substitute outside variables?

[jeffkeller-einc]

It looks like the ability to substitute system variables is limited to the terminal. When I test in Python and R consoles, SUPER_IMPORTANT_DIR resolves to ${env:HOME}/path/to/dir. Is this the case for you as well?

I think this would be a really useful feature. I frequently have environment variables defined at some higher level (Positron user settings in this case) that would be convenient to reference when defining workspace-level environment variables.

[samclark2015]

Yep - I see the same behavior in the Console, too. That said, I think there are two aspects here:

• Variables should be able to reference other variables defined in Positron (Environment: Referencing other variables defined in Positron #9122)
• Console should be able to resolve variables in other variables, like the Terminal does (Console: Variables within contributed environment variables do not resolve  #9123 )

I went ahead and opened some issues to reflect those. You can add any other thoughts or info over there, and give it a 👍 for visibility!