Re: [Help-smalltalk] MethodWrapper

[Paolo Bonzini]

On 10/19/2010 11:00 AM, Gwenaël Casaccio wrote:
> Hi,
> 
> I've made (very) small patch for the VM to support methodWrapper.
> MethodWrapper are objects used to add behavior before and after
> the method evaluation.
> 
> This patch ensure that the vm doesn't cast the object to the class format and
> thus having wrong ivar offset. It also avoids the method check.
> 
> It is useful for pre and post conditions, test coverage.
> 
> You could find the patch at
> 
> git://github.com/MrGwen/smalltalk.git commit  660a66613e62f8d5236f

This is already supported (see examples/Methods.st), you only need
to subclass from CompiledMethod (you saw why :)) and create the
instance with the class method #numArgs:.

The method will be sent #valueWithReceiver:withArguments:.

examples/Methods.st even includes a basic port of MethodWrapper
itself.  You need this to fix bitrot:

diff --git a/examples/Methods.st b/examples/Methods.st
index 67bdbcf..d80d9a6 100644
--- a/examples/Methods.st
+++ b/examples/Methods.st
@@ -45,6 +45,7 @@ test
     "InterpretedMethod test"
     | b |
     b := Behavior new.
+    b superclass: Object.
     b interpretedMethodAt: #testInterp1 put: #(#push 3 #push 4 #add #return).
     b interpretedMethodAt: #testInterp2 put: #(#push 6 #push 7 #mul #return).
     Transcript show: '3 + 4 = '. b new testInterp1 printNl.

Paolo