On 29/11/2010, at 11:28 AM, Etienne Studer wrote:
> Hi
>
> Is it by design that excluding a task with -x on the cmd line behaves
> differently from disabling a task in the code with task.enabled = false. -x
> does smart merging, task.enabled = false does not.
They are intended to work differently.
There are 2 points in the Gradle lifecycle that we care about whether a task
should be executed:
* When we assemble the task graph. The -x option works at this point by vetoing
tasks being added to the task graph.
* Immediately before the task is to be executed. The enabled flag and the
onlyIf predicates are applied at this point. The idea is that these are to be
used if there is some dynamic constraint on the task's execution which cannot
be determined until all the dependencies of the task have been executed. They
are not intended to exclude tasks from the graph.
So perhaps we are missing is some way to exclude a task from being added to the
task graph. Some options:
1. Add an included flag and an includeOnlyIf { } method, which are evaluated
when the task graph is assembled.
2. Move the evaluation of onlyIf { } to task graph assembly time. To check at
execution time, you would use a task action that throws a
StopExecutionException.
3. Make it easier to define conditional dependencies. Then, you exclude a task
by having nothing depend on it.
4. Improve plugins so that we need to use 'enabled = false' less often.
5. Allow the evaluation of onlyIf {} to float, so that it happens as soon as
possible, but not necessarily when the task graph is assembled. Gradle would
execute only those dependencies (if any) which are required to figure out if
the task is required or not. This would fit quite well with the changes being
proposed in
http://docs.codehaus.org/display/GRADLE/Gradle+1.0+Build+Configuration+DSL
My preference would be options 3 and 4, and 5 in the longer term.
--
Adam Murdoch
Gradle Developer
http://www.gradle.org
CTO, Gradle Inc. - Gradle Training, Support, Consulting
http://www.gradle.biz
