Hi Adam,
On May 3, 2009, at 11:05 AM, Adam Murdoch wrote:
Hi,
I'd like to get some feedback on the new task definition DSL I've
added to trunk.
The changes replace the createTask() method with a keyword style
syntax for use in build scripts, and a groovy-ish API for use
elsewhere.
The new syntax is:
task <task-name> [(option...)] [ { action } ]
Some examples:
task aTask // was createTask('aTask')
task aTask { do stuff } // was createTask('aTask') { do stuff }
task aTask(type: Copy, dependsOn: someOtherTask) // was
createTask('aTask', type: Copy, dependsOn: someOtherTask)
task aTask(dependsOn: anotherTask) { do stuff } // you can figure
this one out
More examples in the user guide at
http://gradle.org/userguide/latest/tutorial_using_tasks.html
This looks very nice. Task declarations are the bread and butter of
the build scripts. Making the declaration of them as convenient and
readable and nice as possible is important. I'm very happy with this.
One thing to note is that this syntax works only for statements. It
does not work for expressions. That is, you can't do:
Task someVar = task aTask
For one thing, this isn't actually valid groovy. It would have to
look like:
Task someVar = task(aTask)
Groovy user's are used to the parentheses issue. Sometimes you need
them and sometimes not. We have the same issue in our dependencies
declaration. You need parentheses if you use the map notation and have
multiple map arguments.
which defeats the purpose, I think. It also looks a lot like a call
to the Project.task() method, which is confusing, I think:
Task someVar = task('anExistingTask')
The project task method is rarely used in a build script. You need it
if your task names don't obey to valid Groovy variable names or if
there is some shadowing going on. So why not renaming the Project.task
method to Project.getTask. Then we could provide task(taskName) for
the usage in statements and in a fluent API manner without causing
confusion. The use cases for this are not common but also not
extremely exotic. And you wouldn't have to fall back to a completely
different syntax.
- Hans
or worse:
taskName = 'anExistingTask'
Task someVar = task(taskName) { configure the task }
For both these reasons, I've limited the syntax to statements.
For defining a task in an expression, or in classes outside the
build script, you can use the API on TaskContainer:
tasks.add(name: 'aTask') // replaces createTask('aTask')
tasks.add(name: 'aTask') { do something }
tasks.add(name: 'aTask', type: Copy)
Finally, Project.createTask() will be deprecated in the 0.6 release,
and removed some time after the release.
Comments?
Adam
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Hans Dockter
Gradle Project lead
http://www.gradle.org
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