Classes and Functions - General Questions

[Andreas Hartl]

Setash schrieb:

> 2) Function overloading - is it possible?
> 
> Can I have the following code, or something which acts the same in
> python?:
> 
> 
> def function(a, b)
>    do things
> 
> def function(a, b, c)
>    do things only if I get a third argument

Several ways. The simplest and often most feasible is to create a 
3-argument function with a default value for its last argument

def function(a, b, c=None):
   if c is None:
     do things you need to do with the third argument
   else:
     do things


Alternatively, you may use a *params argument that consumes an arbitrary 
number of arguments

def function(*params):
   if len(params) == 2:
     do 3-argument things
   elif len(params) == 3:
     do 2-argument things

You can of course mix and match *params with preceding parameters.


There is a third option - an experimental dynamic function overloading 
module, see BDFL's weblog 
<http://www.artima.com/weblogs/viewpost.jsp?thread=155514>:

from overloading import overloaded

@overloaded
def function(a, b):
   do things

@function.register(object, object, object)
def function_3(a, b, c):
   do things with 3 parameters


However, I would not recommend this last solution unless you have a 
really, really weird problem that also heavily depends on the type of 
parameters. Simply stick to the first one, this will be sufficient for 
 >90% of all cases.

Andreas