[Tutor] "Overloading" methods

[Vince Spicer]

On Thu, Sep 16, 2010 at 6:02 AM, Michael Powe <michael at trollope.org> wrote:

> Hello,
>
> Strictly speaking, this isn't overloading a method in the way we do it
> in Java.  But similar.  Maybe.
>
> I am writing a module for processing web server log files and one of
> the methods I provide is to extract a given query parameter and its
> value. Because there are several types of log files with different
> line structures, I had the thought to write methods with descriptive
> names that simply returned a generic method that processed the method
> arguments. e.g.,
>
> def setpattern_iis(self,pattern,parameter) :
>        type='iis'
>        return pattern_generator(self,type,pattern,parameter)
>
> In this case, creating a regular expression to parse the log lines for
> a query parameter.
>
> This is just a bit more "self documenting" than using the generic
> method with the 'type' argument and requiring the user to enter the
> type.  At the same time, it allows me to put all the parsing code in
> one method.
>
> My question is, is this a bad thing to do in python?
>
> Thanks.
>
> mp
>
> --
> Michael Powe            michael at trollope.org            Naugatuck CT USA
> War is a sociological safety valve that cleverly diverts popular
> hatred for the ruling classes into a happy occasion to mutilate or
> kill foreign enemies. - Ernest Becker
>
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>
Well I can't comment on right or wrong I would think creating a simple class
with a __call__ method is a
little more pythonic.

Example:

class PatternGenerator(object):
    """Run a regex....."""
    def __init__(self, type_):
        self.type = type_
    def __call__(self, pattern, parameter):
        return pattern_generator(self, self.type, pattern, parameter)

# Initialize class
setpattern_iis = PatternGenerator('iis')

# call the method here
setpattern_iis("pattern", "params")

Hope that helps,

Vince
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