go-task/docs/docs/experiments/any_variables.md

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/experiments/any-variables/

Any Variables

• Issue: #1415
• Environment variable: TASK_X_ANY_VARIABLES=1
• Breaks:
  • Dynamically defined variables (using the sh keyword)

Currently, Task only supports string variables. This experiment allows you to specify and use the following variable types:

• string
• bool
• int
• float
• array
• map

This allows you to have a lot more flexibility in how you use variables in Task's templating engine. For example:

Evaluating booleans:

version: 3

tasks:
  foo:
    vars:
      BOOL: false
    cmds:
      - '{{if .BOOL}}echo foo{{end}}'

Arithmetic:

version: 3

tasks:
  foo:
    vars:
      INT: 10
      FLOAT: 3.14159
    cmds:
      - 'echo {{add .INT .FLOAT}}'

Ranging:

version: 3

tasks:
  foo:
    vars:
      ARRAY: [1, 2, 3]
    cmds:
      - 'echo {{range .ARRAY}}{{.}}{{end}}'

There are many more templating functions which can be used with the new types of variables. For a full list, see the slim-sprig documentation.

Looping over variables

Previously, you would have to use a delimiter separated string to loop over an arbitrary list of items in a variable and split them by using the split subkey to specify the delimiter:

version: 3

tasks:
  foo:
    vars:
      LIST: 'foo,bar,baz'
    cmds:
      - for:
          var: LIST
          split: ','
        cmd: echo {{.ITEM}}

Because this experiment adds support for "collection-type" variables, the for keyword has been updated to support looping over arrays directly:

version: 3

tasks:
  foo:
    vars:
      LIST: [foo, bar, baz]
    cmds:
      - for:
          var: LIST
        cmd: echo {{.ITEM}}

This also works for maps. When looping over a map we also make an additional {{.KEY}} variable availabe that holds the string value of the map key. Remember that maps are unordered, so the order in which the items are looped over is random:

version: 3

tasks:
  foo:
    vars:
      MAP:
        KEY_1:
          SUBKEY: sub_value_1
        KEY_2:
          SUBKEY: sub_value_2
        KEY_3:
          SUBKEY: sub_value_3
    cmds:
      - for:
          var: MAP
        cmd: echo {{.KEY}} {{.ITEM.SUBKEY}}

String splitting is still supported and remember that for simple cases, you have always been able to loop over an array without using variables at all:

version: 3

tasks:
  foo:
    cmds:
      - for: [foo, bar, baz]
        cmd: echo {{.ITEM}}

Migration

Taskfiles with dynamically defined variables via the sh subkey will no longer work with this experiment enabled. In order to keep using dynamically defined variables, you will need to migrate your Taskfile to use the new syntax.

Previously, you might have defined a dynamic variable like this:

version: 3

task:
  foo:
    vars:
      CALCULATED_VAR:
        sh: 'echo hello'
    cmds:
      - 'echo {{.CALCULATED_VAR}}'

With this experiment enabled, you will need to remove the sh subkey and define your command as a string that begins with a $. This will instruct Task to interpret the string as a command instead of a literal value and the variable will be populated with the output of the command. For example:

version: 3

task:
  foo:
    vars:
      CALCULATED_VAR: '$echo hello'
    cmds:
      - 'echo {{.CALCULATED_VAR}}'

If your current Taskfile contains a string variable that begins with a $, you will now need to escape the $ with a backslash (\) to stop Task from executing it as a command.