What's the correct way to create anonymous subclasses in Pharo?

> Hi everybody,
>
> I am attempting to create subclasses of existing classes at runtime. They
> must not be in their superclass' list of subclasses, because they have to be
> garbage collected when they are no longer needed.
>
> This is what I tried to create such a class in Pharo 1.0:
>
>    newMeta := (Metaclass new)
>        superclass: Rectangle class
>            methodDictionary: MethodDictionary new
>            format: Rectangle class format;
>        yourself.
>    newClass := (newMeta new)
>        superclass: Rectangle
>            methodDictionary: MethodDictionary new
>            format: Rectangle format;
>        setName: #MyRectangle;
>        yourself.
>    newClass new class == newClass  "--> false"
>
> The result of "newClass new" seems to be an instance of Rectangle, not of
> newClass. The test at the end of the code snippet answers false. When I
> compile a new method in newClass and install it in newClass'
> methodDictionary, an instance will not understand a message with the
> method's selector.
>
> Almost the same code will do what I want in VisualWorks:
>
> | newMeta newClass |
>   newMeta := (Metaclass new)
>        superclass: Rectangle class;
>        methodDictionary: MethodDictionary new;
>        setInstanceFormat: Rectangle class format;
>        yourself.
>    newClass := (newMeta new)
>        superclass: Rectangle;
>        methodDictionary: MethodDictionary new;
>        setInstanceFormat: Rectangle format;
>        setName: #MyRectangle;
>        yourself.
>    newClass new class == newClass  "--> true"
>
> Does anybody have an idea what the problem is and what can be done to
> circumvent it?
>
> Thanks in advance!
> Joachim Geidel
>
>
>
> _______________________________________________
> Pharo-users mailing list
> [hidden email]
> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-users
>

> Am 23.05.10 15:15 schrieb Igor Stasenko:
>> Do you really need to create a meta? > > If not , then you can do just: >
>> > newClass := Rectangle clone. > newClass >   superclass: Rectangle; >
>>   organization: nil; >   methodDict: MethodDictionary new.
> Unfortunately, this doesn’t solve the problem:
>
> | newClass method |
> newClass := Rectangle clone.
> newClass
>   superclass: Rectangle;
>   organization: nil;
>   methodDict: MethodDictionary new;
>   setName: #MyRectangle.
> newClass new class name. "--> #Rectangle"
> newClass new class == newClass. "--> false"

> method := (newClass compile: 'testGhost ^42'
>         classified: nil
>         notifying: nil
>         trailer: newClass defaultMethodTrailer
>         ifFail: [nil]) method.
> newClass addSelectorSilently: #testGhost withMethod: method.
> newClass canUnderstand: #testGhost. "--> true".
> newClass new respondsTo: #testGhost. "--> false"
> newClass new testGhost. "--> Message not understood, should answer 42"
>
> The problem is not the MetaClass (I do need it), but that the new class
> doesn’t create instances of itself, which I find very, very strange.
>
> Best regards,
> Joachim Geidel
>
> _______________________________________________
> Pharo-users mailing list
> [hidden email]
> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-users
>
>

> Am 23.05.10 15:15 schrieb Igor Stasenko:
> > Do you really need to create a meta? > > If not , then you can do just: > > newClass := Rectangle clone. > newClass >   superclass: Rectangle; >   organization: nil; >   methodDict: MethodDictionary new.
> Unfortunately, this doesn’t solve the problem:
>
>> | newClass method |
>> newClass := Rectangle clone.
>> newClass
>>   superclass: Rectangle;
>>   organization: nil;
>>   methodDict: MethodDictionary new;
>>   setName: #MyRectangle.
>> newClass new class name. "--> #Rectangle"
>> newClass new class == newClass. "--> false"
>> method := (newClass compile: 'testGhost ^42'
>>         classified: nil
>>         notifying: nil
>>         trailer: newClass defaultMethodTrailer
>>         ifFail: [nil]) method.
>> newClass addSelectorSilently: #testGhost withMethod: method.
>> newClass canUnderstand: #testGhost. "--> true".
>> newClass new respondsTo: #testGhost. "--> false"
>> newClass new testGhost. "--> Message not understood, should answer 42"
>
> The problem is not the MetaClass (I do need it), but that the new class doesn’t create instances of itself, which I find very, very strange.
>
> Best regards,
> Joachim Geidel
> _______________________________________________
> Pharo-users mailing list
> [hidden email]
> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-users

> Hi everybody,
>
> I am attempting to create subclasses of existing classes at runtime. They
> must not be in their superclass' list of subclasses, because they have to be
> garbage collected when they are no longer needed.
>
> This is what I tried to create such a class in Pharo 1.0:
>
>    newMeta := (Metaclass new)
>        superclass: Rectangle class
>            methodDictionary: MethodDictionary new
>            format: Rectangle class format;
>        yourself.
>    newClass := (newMeta new)
>        superclass: Rectangle
>            methodDictionary: MethodDictionary new
>            format: Rectangle format;
>        setName: #MyRectangle;
>        yourself.
>    newClass new class == newClass  "--> false"
>
> The result of "newClass new" seems to be an instance of Rectangle, not of
> newClass. The test at the end of the code snippet answers false. When I
> compile a new method in newClass and install it in newClass'
> methodDictionary, an instance will not understand a message with the
> method's selector.
>
> Almost the same code will do what I want in VisualWorks:
>
> | newMeta newClass |
>   newMeta := (Metaclass new)
>        superclass: Rectangle class;
>        methodDictionary: MethodDictionary new;
>        setInstanceFormat: Rectangle class format;
>        yourself.
>    newClass := (newMeta new)
>        superclass: Rectangle;
>        methodDictionary: MethodDictionary new;
>        setInstanceFormat: Rectangle format;
>        setName: #MyRectangle;
>        yourself.
>    newClass new class == newClass  "--> true"
>
> Does anybody have an idea what the problem is and what can be done to
> circumvent it?
>
> Thanks in advance!
> Joachim Geidel
>
>
>
> _______________________________________________
> Pharo-users mailing list
> [hidden email]
> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-users