Dependency-tracking phony/pure tasks with no output files

[quodlibetor]

There are some tasks that don't create deterministic file system outputs (e.g. building docker images) but still have deterministic sources that define when they should be built.

I regularly make tasks that touch a file after success and use that file as the output to avoid unnecessary work in the future. It would, though, be really nice if I could tell mise that task outputs are "pure but non-existent" and have it manage the dependency tracking infrastructure for me.

[jdx]

I don't think I understand this. mise compares the input and the output to know whether or not something should be run. If there is no output, it would run it every time and be equivalent to not specifying any inputs at all.

[quodlibetor]

Yes, that makes sense, I didn't want to describe an implementation in the feature request, but to make it more clear:

What I was imagining is that it would be possible to state that a task is pure (instead of specifying outputs):

[tasks."build:docker"]
run = "docker build src"
sources = "src/**"
pure = true

as this is marked as pure, mise would track the last-build time for task.build:docker (maybe by creating a file in ~/.cache/mise/task-times/task.build:docker, maybe by doing something else) and only re-run it if any of the sources are newer than that tracked time.