How to use environment variables in macro arguments?

[SuniRein]

I want to define a spec like:

name: command
flags:
  --flag: The flag to complete
completion:
  flag:
    flag: ["$file ||| $chdir(~/.local/share/command)"]

But the ~/.local/share/command is actually defined by environment $MY_COMMAND_HOME. I have tried $chdir($(echo $MY_COMMAND_HOME)) and $chdir($MY_COMMAND_HOME) but failed.

Is there an easy way to solve it?

[rsteube]

Specs still have some rough edges so a couple of edge cases might not work.

This seems to be fine though:

name: chdir
flags:
  --flag=: The flag to complete
completion:
  flag:
    flag: ["$files ||| $chdir(${HOME})"]

• = flag suffix to signal that it takes a value
• $files plural
• ${ENV_NAME} curly braces so that it isn't mistaken as macro