Flavio <[EMAIL PROTECTED]> wrote:
> Class soandso:
> def __init__(self):
> self.this = 0
> self.that = 1
> def meth1(self):
> ...
> def meth2(self):
> ...
> def custom(self):
> pass
>
> I want to allow the user to write a python module that declares a
> function so that myprogram can import it and attribute it to the custom
> method of the soandso object. So far so good, that is an easy thing to
> do in Python.
>
> import usermodule
> a=soandso()
> a.custom = usermodule.function
Apparently you haven't tested whether this works. It doesn't:
>>> class Foo(object):
... pass
...
>>> def bar(*args):
... print "bar() got arguments:", args
...
>>> bar("spam", "eggs")
bar() got arguments: ('spam', 'eggs')
>>> Foo.bar_method = bar
>>> Foo.bar_method("spam", "eggs")
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: unbound method bar() must be called with Foo instance as first
argument (got str instance instead)
> But, what if the method had to access the self attributes (self.this
> and self.that) of the soandso object?
To become a method, the function must be bound to an instance, and the
method will then receive the instance as the first argument when
called as a method.
To do this on an already-defined function, use new.instancemethod.
>>> import new
>>> help(new.instancemethod)
--
\ "One time a cop pulled me over for running a stop sign. He |
`\ said, 'Didn't you see the stop sign?' I said, 'Yeah, but I |
_o__) don't believe everything I read.'" -- Steven Wright |
Ben Finney
--
http://mail.python.org/mailman/listinfo/python-list
