Guido's new method definition idea

anthony.tolle at anthony.tolle at
Mon Dec 8 18:01:18 CET 2008

On Dec 6, 4:15 pm, Carl Banks <pavlovevide... at> wrote:
> On Dec 6, 12:47 am, "Patrick Mullen" <saluk64... at> wrote:
> > Could I do something like this:
> > def a.add(b): return a+b
> > Outside of a class?  Of course then that makes you think you could do
> > 5.add(6) or something craaaazy like that.  (I mean, you can do
> > (5).__add__(6) but that's something else entirely)
> I'd be inclined to think that this defines an instancemethod on an
> existing object a.  In other word, I'd read the following two lines as
> more or less equivalent.
> def a.add(b): return a+b
> a.add = lambda b: a+b
> Just as the following are equivalent:
> def foo(): return bar
> foo = lambda: bar
> I had been -0 on this, but now I think I'm -1.

This brings up another question, what would one use when referencing
method names inside the class definition?:

class C:
    def self.method(arg):
        self.value = arg
    def self.othermethod(arg):
        self.value = arg
    # do this?
    funcs = (self.method, self.othermethod)
    # or this?
    funcs = (method, othermethod)

On another related note, I would be interested in seeing this syntax
adopted for the very purpose Carl hinted at...

Normally, if I'm defining a nested function that needs to be stored as
an object attribute, I have to use a dummy name, like the following:

class C:
    def createfunc(self, arg):
        def _dummy(arg):
             return arg + 1
        self.func = _dummy

It would be nice to be able to do the following instead:

class C:
    def createfunc(self):
        def self.func(arg):
            return arg + 1

Or, after the class definition is done, to extend it dynamically:

def C.method(self, arg):
    self.value = arg

...which would be the equivalent of the following:

def method(self, arg):
    self.value = arg
C.method = method

Since functions are first-class objects, it seems perfectly reasonable
to me.

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