«

I'm writing a class, where one of the methods is kinda complex. The
method uses a function which I know for certain will not be used
anywhere else. This function does not require anything from self, only
the args passed by the method.

Where should I put the function?

a) Inside the module but outside the class (to avoid cluttering it;
besides the function does not require to access any property or method
of the class).

# mymodule.py

def _myfunction():
...

class myclass(object):
def mymethod(self):
...
spam = _myfunction()
...


b) Inside the class but outside the method

# mymodule.py

class myclass(object):
def _myfunction(self):
...

def mymethod(self):
...
spam = self._myfunction()
...

c) Inside the method:

# mymodule.py

class myclass(object):
...
def mymethod(self):
def _myfunction(self):
...
...
spam = self._myfunction()
...


I'm new to python (and couldn't find anything about this in PEP .
What would you suggest me?

Thanks
Sergio

Sergio Correia schrieb:
> I'm writing a class, where one of the methods is kinda complex. The
> method uses a function which I know for certain will not be used
> anywhere else. This function does not require anything from self, only
> the args passed by the method.
>
> Where should I put the function?
>
> a) Inside the module but outside the class (to avoid cluttering it;
> besides the function does not require to access any property or method
> of the class).
>
> # mymodule.py
>
> def _myfunction():
> ...
>
> class myclass(object):
> def mymethod(self):
> ...
> spam = _myfunction()
> ...
>
>
> b) Inside the class but outside the method
>
> # mymodule.py
>
> class myclass(object):
> def _myfunction(self):
> ...
>
> def mymethod(self):
> ...
> spam = self._myfunction()
> ...
>
> c) Inside the method:
>
> # mymodule.py
>
> class myclass(object):
> ...
> def mymethod(self):
> def _myfunction(self):
> ...
> ...
> spam = self._myfunction()
> ...
>
>
> I'm new to python (and couldn't find anything about this in PEP .
> What would you suggest me?

If it really has no other use as in this class, put it as an
instancemethod in there. Alternatively, you _could_ nest it like this:

class Foo(object):

def bar(self):
def my_long_important_method(argument):
pass
pass


Diez

Diez B. Roggisch:
> If it really has no other use as in this class, put it as an
> instancemethod in there. Alternatively, you _could_ nest it like this:

Using an instancemethod may be the most formally correct solution for
that problem, but often nested function are the simpler solution. A
downside of nested functions is that you can't give them a doctest (in
a simple way).

Bye,
bearophile

Sergio Correia a écrit :
> I'm writing a class, where one of the methods is kinda complex. The
> method uses a function which I know for certain will not be used
> anywhere else. This function does not require anything from self, only
> the args passed by the method.
>
> Where should I put the function?

Somewhere in your module ?-)

(snip)

If your problem is to reduce the apparent complexity of the method,
defining the function inside the method won't help that much (unless the
function by itself is short enough - and event then...). Apart from
having a direct access to the method's namespace, you don't gain much by
doing so. And if it's a an implementation function that doesn't need to
access the instance, it has no reason to be a method. Moreover, since
it's not part of neither the class or the module interface, you can
freely change your mind if and when you find a need to do so.

I also found out I can't use `unittest` with nested functions

Thank you all for the responses,

Best,
Sergio

On 7 Mar 2007 14:57:54 -0800,
<> wrote:
> Diez B. Roggisch:
> > If it really has no other use as in this class, put it as an
> > instancemethod in there. Alternatively, you _could_ nest it like this:
>
> Using an instancemethod may be the most formally correct solution for
> that problem, but often nested function are the simpler solution. A
> downside of nested functions is that you can't give them a doctest (in
> a simple way).
>
> Bye,
> bearophile
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>