Skip,
> >> TypeError: Button.__cmp__(x,y) requires y to be a 'Button', not a 'instance'
>
> A brief conversation with Guido cleared up what was happening. In my class
> hierarchy I didn't implement __cmp__, but I did implement __getattr__, which
> was delegating most things to the underlying Gtk widget, so
>
> b.__cmp__(l)
>
> became
>
> b._real_widget.__cmp(l)
>
> which then barfed.
>
> Writing a __cmp__ method that does the right thing cleared up the problem.
Delegating magic methods to another instance rarely is a good idea.
Instead of writing a __cmp__, why not fix the wrong `__getattr__`
method? Otherwise you'll run into troubles again. Some things
immediately come to mind:
- Did you redefine __hash__, too? If not, putting your classes into a
dictionary might lead to nasty surprises.
- Someday, James defines a __eq__ method for GObject, and you start
all over again...
- Python grows some additional magic and code that used to work
suddenly breaks with bizarre messages...
I've come to the conclusion that most __getattr__ implementations
delegating to other objects should start with:
if name.startswith ("__") and name.endswith ("__") :
raise AttributeError, name
If you want to delegate magic methods, list the names to be delegated
explicitly.
Christian
PS: I'd hope that you take another look at the `__getattr__`
implementation I proposed 6 weeks ago.
--
Christian Tanzer [EMAIL PROTECTED]
Glasauergasse 32 Tel: +43 1 876 62 36
A-1130 Vienna, Austria Fax: +43 1 877 66 92
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