How to determine whether any prerequisite tasks needed to run at the time they were defined?
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Description
I have a use-case in which I need to run a task if and only if at least one of its prerequisite tasks either (1) currently needs to run or (2) needed to run at the time the prerequisite task was defined. Here are some attempts at a Rake::Task subclass:
class MyTask < Rake::Task
def needed?
prerequisite_tasks.any?(&:needed?)
end
end
This approach does not work, since at the time MyTask#needed? is called, prerequisite tasks may have run and therefore return false for #needed?.
class MyTask < Rake::Task
def needed?
prerequisite_tasks.any? { |p| p.needed? or p.already_invoked }
end
end
This also doesn't work, since #already_invoked can return true [even if the task's #execute method was never called]:
@already_invoked = true
invoke_prerequisites(task_args, new_chain)
execute(task_args) if needed?
What ended up working was:
class MyTask < Rake::Task
def initialize(*)
@needed = false
super
end
def enhance(*)
super.tap { @needed |= prerequisite_tasks.any?(&:needed?) }
end
def needed?
@needed
end
end
But that just feels... wrong. Is there something I'm missing here? I'd be more than happy to open a PR implementing what I'm looking for (maybe an #already_executed method?) if this functionality doesn't already exist.
Thanks!
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Research direction
Start with the Rake::Task entry points shown in the issue: #needed?, #already_invoked, #execute, #enhance, and invoke_prerequisites. Trace when each state changes and determine how to distinguish a prerequisite that was actually executed from one that was only invoked. Done means the behavior is specified and covered by tests for both cases.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- ruby
- Domain
- build-system
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 42/100