Feature Request: define own placeholders

[Marty56]

I have to use the .zprofile file to define top level folder location.
In my rule files I am referencing these definition e.g.

  - locations: 
      - $SOURCE/steuerrelevante Rechnungen

I think this is not the right place to define these variables and would prefer the ability to define in example above SOURCE within the rule file.

[tfeldmann]

I can see the need for that. Goes on the todo list.

[xdhmoore]

One example I ran into with this was I wanted to swap between 2 configurations (test and actual) - each with it's own group of source folders and own destination. From what I understand, the only real place you can define a set of locations is in the config file. It's awkward to set more than one in an environment variable. And I don't see a way to define a destination folder in a single place in the config file. Only by passing it in as an environment variable or working directory flag from my powershell profile. So, I was stuck with having to update both the config file and your shell profile to make the switch.

My current workaround was making the yaml file a jinja2-cli template. But having the ability to set a placeholder I think would have solved this for me.