On Sun, 07 Apr 2013 10:52:11 +0000, Steven D'Aprano wrote:
> On Sun, 07 Apr 2013 09:50:35 +0000, Helmut Jarausch wrote:
>
>> Hi,
>>
>> I'm trying to port a class to Python3.3 which contains
>>
>> class Foo :
>> ....
>> def to_binary(self, *varargs, **keys):
>> ....
>> ....
>> self.to_binary = new.instancemethod(to_binary, self, self.__class__)
>> # Finally call it manually
>> return apply(self.to_binary, varargs, keys)
>
>
> I do not understand this code. Can you give a short example that actually
> works please?
>
> As written, your code has a class that defines a to_binary method. Then,
> *outside* of the method, in the class definition, you refer to "self",
> and use a return statement. This is not possible -- self does not exist,
> and return gives a SyntaxError.
>
> But, if the indentation is wrong, it looks like you are trying to get the
> to_binary method to replace itself with a global to_binary function. I do
> not understand this.
Sorry, the first excerpt was to too short.
As noted in the reply to Arnaud, a better excerpt is:
class Foo :
....
def to_binary(self, *varargs, **keys):
....
code= ...
args= ...
# Add function header
code = 'def to_binary(self, %s):\n' % ', '.join(args) + code
exec(code)
self.to_binary = new.instancemethod(to_binary, self, self.__class__)
return self.to_binary(*varargs, **keys)
If you'd like to see the full code (not by me)
please see the Python package http://python-xlib.sourceforge.net/
file Xlib/protocol/rq.py method to_binary in class Struct
>
> I cannot answer your question, because I don't understand it. But perhaps
> this will help:
>
>
> # === Python 2 version ===
> class Spam:
> pass
>
> x = Spam()
>
> def method(self, arg):
> return {arg: self}
>
> import new
> x.method = new.instancemethod(method, x, x.__class__)
>
> x.method("hello")
> => returns {'hello': <__main__.Spam instance at 0xa18bb4c>}
>
>
> Here is the Python 3 version:
>
>
> # === Python 3 ===
> class Spam:
> pass
>
> x = Spam()
>
> def method(self, arg):
> return {arg: self}
>
> import types
> x.method = types.MethodType(method, x)
>
> x.method("hello")
> => returns {'hello': <__main__.Spam object at 0xb7bc59ac>}
>
>
>
> Does this help?
Yes,
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