Task: Clear variables cache between runs when watching?

[craighurley]

If I run a task that watches foo.txt for changes, I would like to dynamically set a var on every execution/change to foo.txt, however I cannot get it to work with this example configuration; DYN_VAR always remains set the first value of date.

OS: macos 10.15.5

$ task --version
Task version: 3.0.0

version: '3'

tasks:
  foobar:
    sources:
      - ./foo.txt
    generates:
      - ./bar.txt
    vars:
      DYN_VAR:
        sh: date
    cmds:
      - echo "{{.DYN_VAR}}" > ./bar.txt

$ task foobar -w
task: Started watching for tasks: foobar
task: echo "Sat Aug 22 23:25:20 NZST 2020" > ./bar.txt
task: Task "foobar" is up to date
# changes manually made to foo.txt
task: echo "Sat Aug 22 23:25:20 NZST 2020" > ./bar.txt
task: Task "foobar" is up to date

Is it possible to do what I am trying, if so how?

[andreynering]

Hi @craighurley,

That happens because variables are cached in the first run.

We should probably re-evaluate that on every run.

[dschissler]

Try this.

version: '3'

tasks:
  foobar:
    sources:
      - ./foo.txt
    generates:
      - ./bar.txt
    cmds:
      - |
        DYN_VAR=$(date)
        echo "$DYN_VAR" > ./bar.txt

[craighurley]

Thanks @dschissler, that works.