before methods

I've been working on some code using Proxies to step in front of  
method calls and now have an explosion of Proxy objects that
aren't doing anything to make the design clearer. Far from it ( see  
previous thread 'locking' an object ).

I've come back around to my initial inspiration for the design...  
CLOS's before, after and around methods.
Is there are a way to get the same functionality in Smalltalk without  
using a Proxy class?

In order to make it work, I'd have to be able to hook in to the  
standard vm message passing which all
seems to be implemented in primitives which doesn't leave me very  
hopeful that it can be done,
however, the rewards in my case would be great, so I'm here asking...

Is it possible to implement before, after etc methods in Smalltalk?


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Hi Sean,

there's AspectS and ContextS. Those two should provide what you need.
Right now, the available release of AspectS is a bit aged, but
accessible from
http://map.squeak.org/package/e640e9db-2f5f-4890-a142-effebda68748. A
ContextS release is in preparation.

Best,

Michael
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Hi again,

On Sun, Oct 12, 2008 at 1:03 PM, Michael Haupt <[hidden email]> wrote:
> A ContextS release is in preparation.

no wait. There|s http://www.hirschfeld.org/misc/index.html#code :-)

Best,

Michael
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The standard thing to do is to use MethodWrappers.

Another possibility is to create a custom CompiledMethod implementing
#valueWithReceiver:arguments: and delegating to the original compiled
method.

Cheers,
Lukas

On 10/12/08, Michael Haupt <[hidden email]> wrote:

--
Lukas Renggli
http://www.lukas-renggli.ch
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On Sat, Oct 11, 2008 at 08:08:15PM -0400, Sean Allen wrote:
yes. Make a subclass.

overriddenMethod
    Transcript show: 'This is the before aspect'; cr.
    super overriddenMethod
    Transcript show: 'This is the after aspect'; cr.

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Matthew Fulmer -- http://mtfulmer.wordpress.com/
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On Oct 12, 2008, at 12:13 PM, Matthew Fulmer wrote:

> yes. Make a subclass.
>
> overriddenMethod
>    Transcript show: 'This is the before aspect'; cr.
>    super overriddenMethod
>    Transcript show: 'This is the after aspect'; cr.

should have been more clear on that.

want to go in the opposite direction.

with CLOS before methods you can do something like this.

base...

before x
x

before x does foo
x does nothing

child

implements x

child b

implements x

both children get the before x functionality run before their x  
without having to explicitly call.

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