On Aug 7, 2008, at 1:22 PM, Adam Murdoch wrote:
Hans Dockter wrote:
On Aug 6, 2008, at 12:12 PM, Adam Murdoch wrote:
Hans Dockter wrote:
What about doing things differently?
We could introduce a Configuration class which implements Task.
One can add dependencies to a configuration. Executing such a
task means resolving its dependencies. Such a task would offer
also methods to get a path, list of files, etc ... The compile
task for example would depends on its configuration task(s). A
project dependency would establish a depends relation between
the configuration it belongs to and the configuration of the
other project. The artifact producing configuration of the other
project would depend on the corresponding artifact task(s).
This would remove unnecessary elements from our API. It
decreases the learning curve and simplifies the design. Last but
not least we have finally our Configuration object to express
this important domain concept.
I think this is an excellent idea. We already do something
similar (conceptually) for bundles: A task is added to the
project for each bundle produced by the project, and I can ask
that a bundle be built from the command-line, add dependencies on
it, query it for its location, etc. We could probably come up
with a common approach for configurations and bundles.
A bundle is a task and at the same time a container for archive
tasks on which it depends. Your analogy is that a configuration is
a container for dependencies, right?
Sorry, I meant to say archives instead of bundles, ie we do
something similar for archives (make them available as tasks which
other tasks can depend on). Hopefully that makes more sense.
I'm not sure if Configuration should implement Task, or whether
adding a Configuration would trigger the adding of a Task that
resolves it. The problem with implementing Task is that there
are (at least) 2 interpretations of 'executing' a configuration:
resolving it, and producing/publishing it. By adding a task
instead, we have the option of adding both a resolve task and a
publish task for a configuration. I guess another option would be
to have 2 types of Configuration: one for incoming dependencies
and one for produced artifacts.
In Ivy itself all configurations are equals. They may contain only
external dependencies or only artifacts produced by the project or
both (e.g. a configuration that exposes the artifacts of a
projects plus its external dependencies). I'm not sure if Ivy
misses to model an important concept.
Our configurations could take the same approach as Ivy. The fact
that a configuration contains artifacts to be produced by the
project can be expressed by the fact that this configuration
depends on the respective archive task. A resolve could be simply
defined by calling an Ivy resolve for the underlying Ivy
ocnfiguration.
This makes sense. So, for example, if I have a project that
produces an artifact and includes it in a configuration, I add an
Archive (task) to produce the artifact, then add a Configuration
(task) with a dependency on the archive task. Adding this
dependency declares that the archive is a publication included in
the configuration.
If I want to use the configuration in my project, I add another
task with a dependency on the configuration task. Adding this
dependency declares that the task uses the configuration. Before my
task is executes, the archive is built, the configuration is
resolved, and my task can query the Configuration object for the
files that make up the configuration.
If I want to include artifacts from another project, I can add a
dependency from the configuration task to a configuration task in
the other project.
Right. With the current design we would use an intermediary for doing
this. A project dependency would establish the dependency between the
two configurations of the respective projects. The project dependency
has the additional job to translate this dependency into ivy language.
I can add more artifacts to the configuration by adding more
dependencies on archive tasks (or any file producing task, really).
I can add external dependencies (log4j, say) by adding them
directly to the configuration task.
Where do you think publishing would happen in all this?
Publishing in the sense of adding an artifact to a repository happens
in the uploadLibs and uploadDists tasks. I'm not sure if it was a
good idea to introduce a new term 'upload' for this instead of using
the term 'publish'.
The remaining open issue is how to deal with cleaning. Building a
dependency without cleaning is not that reliable. This is a
(modified) quote from one of my earlier emails:
One more point we need to think about. If we do a partial build of
project A which has a project dependency on project B. Let's say we
execute 'gradle clean libs'. Project A is cleaned before its libs
are created, not so project B. Only the artifact producing task is
executed. We could declare an additional dependsOn('projectB') in
project A. Such a dependsOn establishes task dependencies between
tasks with similar names of both projects. Now the clean is done
for both projects but also the libs task is executed for project B
which would neutralize our effort to become more fine-grained
regarding project dependencies artifacts.
- Hans
--
Hans Dockter
Gradle Project lead
http://www.gradle.org
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