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From: Richard Lamboj on 29 Apr 2010 03:55

Hello,

i want to add functions to an instance of a class at runtime. The added
function should contain a default parameter value. The function name and
function default paramter values should be set dynamical.

Kind Regards,

Richi
From: James Mills on 29 Apr 2010 04:12
On Thu, Apr 29, 2010 at 5:55 PM, Richard Lamboj
<richard.lamboj(a)bilcom.at> wrote:
> i want to add functions to an instance of a class at runtime. The added
> function should contain a default parameter value. The function name and
> function default paramter values should be set dynamical.

The normal way of doing this by binding a new
MethodType to an instance:

>>> class A(object):
.... def foo(self):
.... return "foo"
....
>>> def bar(self):
.... return "bar"
....
>>> a = A()
>>> a.foo()
'foo'
>>> a.bar()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'A' object has no attribute 'bar'
>>> from types import MethodType
>>> setattr(a, "bar", MethodType(bar, a))
>>> a.bar()
'bar'
>>> a.foo
<bound method A.foo of <__main__.A object at 0x8380e8c>>
>>> a.bar
<bound method ?.bar of <__main__.A object at 0x8380e8c>>
>>>

cheers
James
From: Peter Otten on 29 Apr 2010 04:13
Richard Lamboj wrote:

> i want to add functions to an instance of a class at runtime. The added
> function should contain a default parameter value. The function name and
> function default paramter values should be set dynamical.

>>> class A(object):
.... def __init__(self, x):
.... self.x = x
.... def m(self):
.... return self.f(self.x)
....
>>> a = A(42)
>>>
>>> def foo(self, a, b):
.... return self.x + a**b
....
>>> from functools import partial
>>> a.f = partial(foo, a, 3)
>>> a.m()
109418989131512359251L
>>> 42 + 3**42 == _
True

Confused? The important points are

(1)

functools.partial(f, a1, a2, a3, ...)(b1, b2, b3, ...)

is equivalent to

f(a1, a2, a3, ..., b1, b2, b3, ...)

(2)

If you stick a function into an instance

a.f = f

the call

a.f()

will not automagically pass self as the first argument.

Peter
From: Richard Lamboj on 29 Apr 2010 04:15

Am Thursday 29 April 2010 09:59:22 schrieb Xavier Ho:
> On Thu, Apr 29, 2010 at 5:55 PM, Richard Lamboj
<richard.lamboj(a)bilcom.at>wrote:
> > Hello,
> >
> > i want to add functions to an instance of a class at runtime. The added
> > function should contain a default parameter value. The function name and
> > function default paramter values should be set dynamical.
> >
> > Kind Regards,
> >
> > Richi
> > <http://mail.python.org/mailman/listinfo/python-list>
>
> What did you mean by "The function name and function default paramter
> values should be set dynamical." ? Also, have you tried anything we can
> see?
>
> Cheers,
> Xav

No i don't have any sample code.

I just want to add new functions to an class instance at runtime and i also
want to set the default parameter values of this new function.

Dynamical:
Class Test(object):
def add_function(self, function_name="new_function", param="new_param",
value="new_value"):
...

or something like:

Class Test(object):
def add_function(self, function_name="new_function",
parameters=[["param1", "value1"],["param2", "value2"]]):
...

Statical created it would look like:
Class Test(object):
def new_function1(new_parm1="new_value1"):
pass
def new_function2(new_parm2="new_value2"):
pass
def new_function3(new_parm3="new_value3"):
pass

Kind Regards,

Richi
From: News123 on 29 Apr 2010 04:31
Peter Otten wrote:
> Richard Lamboj wrote:
>
>> i want to add functions to an instance of a class at runtime. The added
>> function should contain a default parameter value. The function name and
>> function default paramter values should be set dynamical.
>
>>>> class A(object):
> ... def __init__(self, x):
> ... self.x = x
> ... def m(self):
> ... return self.f(self.x)
> ...
>>>> a = A(42)
>>>>
>>>> def foo(self, a, b):
> ... return self.x + a**b
> ...
>>>> from functools import partial
>>>> a.f = partial(foo, a, 3)
>>>> a.m()
> 109418989131512359251L
>>>> 42 + 3**42 == _
> True
>
> Confused? The important points are
>
> (1)
>
> functools.partial(f, a1, a2, a3, ...)(b1, b2, b3, ...)
>
> is equivalent to
>
> f(a1, a2, a3, ..., b1, b2, b3, ...)
>
> (2)
>
> If you stick a function into an instance
>
> a.f = f


>
> the call
>
> a.f()
>
> will not automagically pass self as the first argument.
>
The drawback would be, that
b = A(123)
b.f()
would still be called with a as bound object.


N

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