Be able to use variables inside variable names

[MetalArend]

Description

tasks:
  do:*:
    vars:
      THING: "{{index .MATCH 0}}"
      _FIRST_THING: "one"
      _SECOND_THING: "two"
    requires:
      vars:
        - name: THING
          enum: [ first, second ]
    cmds:
      - echo "{{.THING}}" # first
      - echo "._{{.THING | upper}}_THING" # ._FIRST_THING
      - echo "{{"{{"}}._{{.THING | upper}}_THING{{"}}"}}" # {{._FIRST_THING}}
      - echo "{{._{{.THING | upper}}_THING}}" # This does not work, should print "one" for `task do:first`

If I would run task do:first, it would be awesome to be able to use the variable THING to get to the parsing of {{._FIRST_THING}} and echo "one" in the last command.

I can get something similar to work when doing an extra call to force a second render, but it would be nice if this could be done in a more direct way.

tasks:
  _do-through-loop:
    requires:
      vars: [OUTPUT]
    cmds:
      - echo "{{.OUTPUT}}"

  do-through-loop:*:
    vars:
      THING: "{{index .MATCH 0}}"
    requires:
      vars:
        - name: THING
          enum: [ first, second ]
    cmds:
      - task: '_do-through-loop'
        vars:
          OUTPUT: '{{"{{"}}._{{.THING | upper}}_THING{{"}}"}}'
          _FIRST_THING: "one"
          _SECOND_THING: "two"

Here's me hoping that second example is not going to be recognised as a bug, and eventually be removed 🤞

[trulede]

@MetalArend the templating is from Go text/template, so far I never encountered nested templates as you have them. You might find another way to solve your problem, something along these lines:

- echo "{{$foo:=.NUMBER}}{{$foo}}" # prints 1 (if .NUMBER is 1)

You can read the documentation, and especially the Go docs (linked at top), to find out more.
https://taskfile.dev/reference/templating/

[MetalArend]

I ended up with the following: you can use {{index . (print (.THING | upper) "_THING")}}. It will first parse .THING, uppercase it, concatenate it with "_THING", and then use the combined string "FIRST_THING" to get that variable from the root ".".