I agree with the misgivings expressed in this post, and I think Guice is
going to be a snazzy mistake, but it was evident pretty quickly that it
was going to be an uphill battle to sell that. I don't have the time
for uphill battles, and I accept the possibility that I just don't get
it. Bob Lee may have sharp elbows, but he's clearly a smart dude, and
Guice is definitely cool. If nothing else I'm concerned that Guice is
not going to enable the kind of creative rewiring that Spring does,
because as I recall you have to anticipate potential customization
points and go out of your way to externalize the wiring. I expect this
would tend to produce a code base that's elegantly modular only from the
inside. I won't mind having some exposure to a project built on Guice
though, so w/e.
Anil Gangolli wrote:
When I read the fine print on the proposal it basically sounds like we
aren't really much real adoption of DI at all, and we are just
introducing the use of Guice to wire the manager layer up.
I still think the choice of Guice over Spring is misguided in our
context. Annotation/code-based injection makes sense for the
manager/persistence wire-up and other component bindings where
non-committing developers are less likely to want to change things
post-distribution, exactly where it's being used in this limited
proposal.
As it stands it's a small step in the DI direction and a more
significant step towards adopting Guice rather than Spring for our DI
basis, kind of the opposite of what I would have liked to see
personally.
If this is a way to get us comfortable with going further with DI, I'm
all for it, because I want to see us go much further along that track.
I'm more interested in the cleanliness, "pluggability" and
"replaceability" we will get by adopting the DI model more fundamentally
throughout Roller.
+1 but with hesitation and another plea to consider Spring.
--a.
On Thu, 2007-06-21 at 09:31 -0400, Elias Torres wrote:
I have been playing with Guice and I'm starting to like it.
+1
-Elias
Dave wrote:
Now that the EZ install/boostrapping work is complete in the trunk
and I've brought the roller_guice branch in line with the new regime,
I'm ready to start talking DI again. This is the last bit of work that
I'd like to get in before the 4.0 release.
Here's the start of the proposal:
This proposal introduces DI in Roller in a pretty limited way. The
idea is to get a DI framework into Roller so we can start rooting out
our various factories and singletons, making the code easier to test,
manage and providing more extension points.
As it stands today it's only benefits are that it 1) allows a
customizer to easily switch out Roller manager classes and replace
them with their own implementations and 2) make it possible for
RollerFactory to instantiate other Roller-dependent classes created by
folks who are customizing Roller.
These requirements are met by this proposal.
* Introduce DI
** Use DI to setup the Roller instance and managers, i.e. manager
classes should no longer be hard-coded into the Roller implementation
class, instead they should be injected.
** Enforce singletons, i.e. singletons should have a private constructor.
** Use constructor injection to ensure that immutable objects remain
immutable.
* Do not change Roller API
** Do not change the was Roller back-end interfaces are accessed by
front-end code
** i.e. RollerFactory.getRoller() stays in place
* Do not change way Roller is configured
** Do not introduce any additional configuration files for those
installing Roller, i.e. don't change the fact that the only
customization file users should ever have to touch is
roller-custom.properties.
** Do not introduce any additional configuration files for developers,
i.e. developers should not have to deal with any new XML or property
files.
** Maintain the same level of back-end pluggability, i.e. it should
still be possible to switch back-end implementations by setting a
single property in the Roller configuration file.
Read the rest here, with
http://cwiki.apache.org/confluence/display/ROLLER/Proposal+Introduce+DI+with+Guice
Comments?
- Dave
