On Apr 5, 2006, at 2:30 AM, James Strachan wrote:
On 4/5/06, David Blevins <[EMAIL PROTECTED]> wrote:
On Apr 4, 2006, at 11:37 PM, James Strachan wrote:
On 4/4/06, David Blevins <[EMAIL PROTECTED]> wrote:
Good point - though before JSR 250 & EJB 3, when Pico was just
starting, I tended to use the convention that contructor arguments
were 'mandatory' properties and setter methods were for optional
stuff
(or stuff that can be configured after construction).
i.e. its kinda implicit that any constructor arguments must be
injected to be able to construct the object - so they are mandatory
already. I guess a container could shove in null objects or zero
values if it can't find a value, but maybe its easier to just say
that
for constructor injection, the parameters should be considered
mandatory?
I get it -- you're using @Resource to imply whether or not an object
attribute is optional or required.
Yeah; Ideally there would be an @Mandatory in JSR 250 on properties...
We're talking about different
things then. Was more going after EJB 3 perspective where @Resource
is primarily used to label an object attribute with an identifier and
optional mapping the injector understands (such as a jndi name, an
xml attribute or element name, or whatever).
Yeah. Though the EJB 3 injection is more like auto-JNDI lookup; the
POJO is kinda pulling resources into itself using the name it defines.
In Spring style, the XML config injects into the POJO without its
particular pre-knowledge. So AnDI is a little attempt to reclaim the
@Resource annotation for non-JNDI style injection where we can just
use it as a marker for what are the mandatory properties.
Exactly. Lot's of stuff could fall under the "whatever" category...
kernel references or just about anything could be named via @Resource
(name="foo"). Heck, if you use a URI in there like I know you would,
you could do anything with it :) I'd be likely to endorse something
sick and twisted like that ;)
Seems like in your scenario, someone couldn't use the annotation to
specify how object attribute would be populated via an injectable
resource but still let it be an optional dependency. Guessing you
don't really care though :)
This is a good point. I'd assumed in EJB 3 land that @Resource implies
mandatory injection; what happens if there is no value available in
JNDI? Is that an error or is null used? If its the latter then maybe
we do need a @Mandatory or @NotNull or something.
Right, EJB 3 says they are mandatory. But thinking along your lines
of slightly repurposing it for better use, you could theoretically
allow someone to label an object attribute via @Resource and still
annotate or flag it as optional somehow. Just a thought.
-David
