I wouldn't try to do
something like this with a constructor -- that would severely change the
semantics of "new", which the caller expects to always return a new instance
of something.
JB> That is what
the tag interface is for (ITransparentSessionCache) – the developer MUST
subscribe explicitly to this caching functionality.
if we force the use
of factories – we would have to develop a significant amount of code just to
use aspectj.
I seen the factory
example in the aspectj in action
(excellent book BTW!!!!)... I am trying to avoid that if I can – I need
something a little more
seamless... at least
until we are through the prototyping/POC stages. Caching on construction would
be a HUGE bonus for us.
I do agree with you
though it could be quite dangerous.... but extremely elegant at the same
time... IMO.
-----Original
Message-----
From:
aspectj-users-admin@xxxxxxxxxxx [mailto:aspectj-users-admin@xxxxxxxxxxx]
On Behalf Of Scott
Stanchfield
Sent: Thursday,
October 21, 2004 12:29 PM
To:
aspectj-users@xxxxxxxxxxx
Subject: RE: [aspectj-users] trying to
write a simple caching aspect
Not sure
how to do something like this with AspectJ, but it raised a red flag for
me:
I
wouldn't try to do something like this with a constructor -- that would
severely change the semantics of "new", which the caller expects to always
return a new instance of something.
If you
had some factory methods that you added caching to, this would be fine (again,
depending on the semantics of the methods), but be careful how things are
documented. If the factory method guarantees a new object (which is what "new"
does), you shouldn't change the semantics like this, as the caller code may
have been written to rely on this behavior.
(This is
one of the things that scares me about AspectJ...)
--
Scott
From:
aspectj-users-admin@xxxxxxxxxxx [mailto:aspectj-users-admin@xxxxxxxxxxx]
On Behalf Of Jody
Brownell
Sent: Thursday,
October 21, 2004 11:18 AM
To:
aspectj-users@xxxxxxxxxxx
Subject: [aspectj-users] trying to
write a simple caching aspect
Hi – I am new
to aspectj, I am working through some example and trying to develop a few
aspects as a proof of concept.
The first aspect I am trying to develop
is a real simple caching aspect which caches objects based on the
implementation of a tag interface.
What I would like to do is when a
constructor is called, check if the class implements an interface, if it
does check the cache. If there is
no reference in the cache, proceed,
cache the object and then return it. Otherwise return the cached
instance.
What I need to be able to do is get the
name of the class the constructor is being called on. My pointcut should
really select all
constructors in the system (maybe
confined to a package) with any number of arguments. Once I have the class
object or the name,
I can determine if the cache should be
consulted.
Is this possible? If so could someone
provide me with an example of the pointcut and advice. I would provide
what I have already but I
am stumped as to how I can capture
class of the object I am trying to instantiate. My problem is I would like
to capture the class as context in
an around advice using a target() like
construct.
Thanks in advance.
Jody b.
