Hello. I am trying to get a handle on how things are are called. I might like to make some changes to standard morphs for my own purposes.
I can put the cursor on a morph, and inspect it, or debug it. Can I put the cursor on it and say "I want this morph, and all of its submorphs, to make a note on the Transcript each time a method is entered?"
Regards, Rick
On 04/04/2011 10:22 PM, Rick H. wrote:
Hello. I am trying to get a handle on how things are are called. I might like to make some changes to standard morphs for my own purposes.
I can put the cursor on a morph, and inspect it, or debug it. Can I put the cursor on it and say "I want this morph, and all of its submorphs, to make a note on the Transcript each time a method is entered?"
Regards, Rick
Not typical beginner stuff, but here goes:
Anything is possible - and my first idea on how to do that was to "wrap" the morph (and all its submorphs individually) in a so called "wrapper" object that delegates all messages to its wrappee - but first prints something of course.
Constructing such a wrapper that is properly "invisible" can be a bit tricky but basically one can create a class inheriting from ProtoObject (instead of Object) which means it will have NO inherited behavior, and then implement doesNotUnderstand: to do the delegation. Such a class will be "utterly stupid" and thus fairly invisible. Things making it complicated are identity - you would need to do the "wrap" using the magical become: message. And you would need to make sure the wrappee doesn't "leak" itself out as an answer to a message - in unwrapped form. As you realize it gets tricky.
Then I remembered that there is something called MethodWrappers that can be used to do similar "augmentation", but on a method by method basis instead of on the object level. I am pretty sure that is a much more bullet proof approach. Haven't used that package myself though.
regards, Göran
On Mon, 4 Apr 2011, Göran Krampe wrote:
On 04/04/2011 10:22 PM, Rick H. wrote:
Hello. I am trying to get a handle on how things are are called. I might like to make some changes to standard morphs for my own purposes.
I can put the cursor on a morph, and inspect it, or debug it. Can I put the cursor on it and say "I want this morph, and all of its submorphs, to make a note on the Transcript each time a method is entered?"
Regards, RickNot typical beginner stuff, but here goes:
Anything is possible - and my first idea on how to do that was to "wrap" the morph (and all its submorphs individually) in a so called "wrapper" object that delegates all messages to its wrappee - but first prints something of course.
Constructing such a wrapper that is properly "invisible" can be a bit tricky but basically one can create a class inheriting from ProtoObject (instead of Object) which means it will have NO inherited behavior, and then implement doesNotUnderstand: to do the delegation. Such a class will be "utterly stupid" and thus fairly invisible. Things making it complicated are identity
- you would need to do the "wrap" using the magical become: message. And you
would need to make sure the wrappee doesn't "leak" itself out as an answer to a message - in unwrapped form. As you realize it gets tricky.
I'm sure this method is sufficient for Rick's goal, but Squeak has a better mechanism for proxies, which allows all real message sends to be captured. Igor wrote some classes* which simplify proxy creation, by implementing the boilerplate stuff. The problem with this method is that older VMs don't fully support this mechanism, but this is definitely the best solution for the future, so expect this to be added to the Trunk soon.
Levente
*http://code.google.com/p/pharo/issues/detail?id=3648
Then I remembered that there is something called MethodWrappers that can be used to do similar "augmentation", but on a method by method basis instead of on the object level. I am pretty sure that is a much more bullet proof approach. Haven't used that package myself though.
regards, Göran _______________________________________________ Beginners mailing list Beginners@lists.squeakfoundation.org http://lists.squeakfoundation.org/mailman/listinfo/beginners
On 07.04.2011, at 04:26, Rick H. wrote:
It sounds like I'm better off doing it manually. Thanks for your help.
Yes. I tried your original idea using ObjectViewer (which provides a generic interceptor of all messages, almost fixed in latest trunk image). But there are just too many messages sent repeatedly to make much sense of it.
You are far better off using the implementors/senders shortcuts which allow you to browse the Squeak code base as a hyper-text system. And ask questions when you get stuck, of course :)
- Bert -
beginners@lists.squeakfoundation.org
-
Bert Freudenberg -
Göran Krampe -
Levente Uzonyi -
Rick H.