use object method without initializing object

[Reckoner]

would it be possible to use one of an object's methods without
initializing the object?

In other words, if I have:

class Test:
def __init__(self):
print 'init'
def foo(self):
print 'foo'

and I want to use the foo function without hitting the
initialize constructor function.

Is this possible?

[colas.francis@gmail.com]

Re: use object method without initializing object

On 15 avr, 17:27, Reckoner <recko...@gmail .comwrote:

would it be possible to use one of an object's methods without
initializing the object?
>
In other words, if I have:
>
class Test:
def __init__(self):
print 'init'
def foo(self):
print 'foo'
>
and I want to use the foo function without hitting the
initialize constructor function.
>
Is this possible?

Yes:

In [214]: class Test:
.....: def foo(self):
.....: print 'foo'
.....:

In [215]: t = Test()

In [216]: t.foo()
foo

[Robert Bossy]

Re: use object method without initializing object

Reckoner wrote:

would it be possible to use one of an object's methods without
initializing the object?
>
In other words, if I have:
>
class Test:
def __init__(self):
print 'init'
def foo(self):
print 'foo'
>
and I want to use the foo function without hitting the
initialize constructor function.
>
Is this possible?
>

Hi,

Yes. It is possible and it is called "class method". That is to say, it
is a method bound to the class, and not to the class instances.
In pragmatic terms, class methods have three differences from instance
methods:
1) You have to declare a classmethod as a classmethod with the
classmethod() function, or the @classmethod decorator.
2) The first argument is not the instance but the class: to mark this
clearly, it is usually named cls, instead of self.
3) Classmethods are called with class objects, which looks like this:
ClassName.class _method_name(.. .).

In your example, this becomes:

class Test(object):
def __init__(self):
print 'init'
@classmethod
def foo(cls):
print 'foo'


Now call foo without instantiating a Test:
Test.foo()

RB

[colas.francis@gmail.com]

Re: use object method without initializing object

On 15 avr, 17:43, Robert Bossy <Robert.Bo...@j ouy.inra.frwrot e:

Reckoner wrote:

would it be possible to use one of an object's methods without
initializing the object?

>

In other words, if I have:

>

class Test:
def __init__(self):
print 'init'
def foo(self):
print 'foo'

>

and I want to use the foo function without hitting the
initialize constructor function.

>

Is this possible?

>
Hi,
>
Yes. It is possible and it is called "class method". That is to say, it
is a method bound to the class, and not to the class instances.
In pragmatic terms, class methods have three differences from instance
methods:
1) You have to declare a classmethod as a classmethod with the
classmethod() function, or the @classmethod decorator.
2) The first argument is not the instance but the class: to mark this
clearly, it is usually named cls, instead of self.
3) Classmethods are called with class objects, which looks like this:
ClassName.class _method_name(.. .).
>
In your example, this becomes:
>
class Test(object):
def __init__(self):
print 'init'
@classmethod
def foo(cls):
print 'foo'
>
Now call foo without instantiating a Test:
Test.foo()

To be complete, you can also define a static method that will not even
be passed the class as argument:

In [217]: class Test(object):
.....: def __init__(self):
.....: print 'init'
.....: @staticmethod
.....: def foo():
.....: print 'foo'
.....:

In [218]: Test.foo()
foo