On 1/3/2024 11:17 PM, Thomas Passin wrote:
On 1/3/2024 8:00 PM, Alan Gauld via Python-list wrote:
On 03/01/2024 22:47, Guenther Sohler via Python-list wrote:
Hi,
In my cpython i have written quite some functions to modify "objects".
and their python syntax is e.g.\
translate(obj, vec). e.g whereas obj is ALWAYS first argument.
However, I also want to use these functions as class methods without
having
to
write the function , twice. When using the SAME function as a methos,
the
args tuple must insert/contain "self" in the first location, so i have
written a function to do that:
I'm probably missing something obvious here but can't you
just assign your function to a class member?
def myFunction(obj, ...): ...
class MyClass:
myMethod = myFunction
Then you can call it as
myObject = MyClass()
myObject.myMethod()
A naive example seems to work but I haven't tried anything
complex so there is probably a catch. But sometimes the simple
things just work?
That works if you assign the function to a class instance, but not if
you assign it to a class.
def f1(x):
print(x)
f1('The plain function')
class Class1:
pass
class Class2:
pass
c1 = Class1()
c1.newfunc = f1
c1.newfunc('f1 assigned to instance') # Works as intended
Class2.newfunc = f1
c2 = Class2()
c2.newfunc('f1 assigned to class') # Complains about extra argument
If your requirements are not very tricky, you can write a
convert-to-method function yourself:
def f1(x):
print(x)
f1('The plain function')
class Class2:
pass
def convert_method(f):
"""Assign existing method without a "self" arg
as a class's method.
"""
def fnew(instance, *args):
f(*args)
return fnew
Class2.newfunc = convert_method(f1)
c2 = Class2()
c2.newfunc('f1 assigned as method of Class2') # Prints the arg
This example does not make f1 aware of the self argument, but you asked
to convert an existing function, and that function would not be aware of
the self parameter. It's much like a decorator function, but is not here
being used as a decorator. If you meant something else, please think out
what you want and explain that.
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