I think your reasoning is sound...!
Scott
Luke Taylor wrote:
> I agree that reusability is important but I'm not convinced that these
> changes are justified on this basis, or that is just about balancing
> reusability and ease of use. The use of constructor arguments is about
> guaranteeing that objects can only be created with a specific state (the
> dependencies required by their design) and providing a single point for
> checking that state (the constructor). This is a design issue based on
> the requirements as determined by the developer at the time they write
> the class. As time goes on and different requirements become apparent
> from forum posts and so on, compromises are made, access is provided to
> state that was previously immutable or unreadable etc etc. The most
> reusable code may provide no-arg constructors and getters and setters
> for everything, but it is also the least stable.
>
> To summarise, there may be situations where we *do* want to open things
> up in this way for some classes, to provide extra extensibility, but I
> don't think accommodating the inadequacies of plexus is sufficient
> justification for a cross-the-board change. Could it not be argued that
> the changes should be made to plexus rather than Acegi?
>
> The plexus web site also says on the main page that it supports
>
> "Various dependency injection techniques including constructor
> injection, setter injection, and private field injection."
>
> so I find that a bit confusing... Is the web site just plain wrong?
>
> Also, is plexus actually used in practice by anyone other than Maven?
>
> As I said before, we have deliberately moved towards the use of
> constructor injection for required dependencies, actually to avoid
> having to use Spring-specific constructs like the InitializingBean
> interface and to facilitate use outside of a Spring application context.
> Removing this will allow users to deploy misconfigured apps which will
> fail when first used rather than at deploy time, which I don't see as an
> improvement.
>
> What do other people think? I'm always interested in discussions about
> guaranteeing the state and integrity of objects and have come to see it
> as more of an important issue as time has passed.
>
>
>
> Luke Taylor wrote:
>
>> Opening this up to the list for discussion
>>
>>
>>
>>> no problem
>>> I don't think it's just a plexus problem, in general it allows
>>> extensibility and reuse. For instance you may want to subclass it with
>>> a different behaviour and the constructor arguments approach is
>>> limiting. At the end it's a matter of balancing ease of use and
>>> reusability
>>>
>>> On 7/12/06, Luke Taylor wrote:
>>>
>>>> I think these kind of changes should be discussed on the list
>>>> beforehand. Ben and I talked about this kind of thing a while back and
>>>> agreed that enforcing initialization of objects with a particular state
>>>> and being able to guarantee their integrity isn't something to be given
>>>> up lightly.
>>>>
>>>> Do you mind if I forward your reply to the list. If we are going change
>>>> this approach to accommodate plexus then it should probably be discussed
>>>> there.
>>>>
>>>> Carlos Sanchez wrote:
>>>>
>>>>> I'm adding Acegi to Continuum and it uses Plexus as IoC (it wasn't me)
>>>>> with the small problem that it doesn't accept constructor arguments.
>>>>> Default constructor+setters are still good to allow extension. I added
>>>>> javadocs to make clear the need of calling the setters later and
>>>>> checks to ensure the object is properly initilized.
>>>>>
>>>>> On 7/10/06, Luke Taylor wrote:
>>>>>
>>>>>> What's with adding all these default constructors? There was some
>>>>>> discussion a while back about using constructor injection for
>>>>>> initialization where possible for required dependencies and avoiding the
>>>>>> use of InitializingBean, setter injection etc...
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>
>>
>>
>
>
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