acting on items passed to a method via a dictiomary

[exarkun at divmod.com]

On Fri, 15 Oct 2004 11:56:12 -0500, Donnal Walter <donnal at donnal.net> wrote:
>The following method is defined in one of my classes:
> 
>      def setup(self, items={}):
>          """perform setup based on a dictionary of items"""
>          if 'something' in items:
>              value = items['something']
>              # now do something with value
>          if 'another' in items:
>              value = items['another']
>              # do something else with value
>          if 'spam' in items:
>              value = items['spam']
>              # do yet another thing with value
>          if 'eggs' in items:
>              value = items['eggs']
>              # and so on
> 
> The purpose is to set up the object based on values contained in a 
> dictionary passed to the setup() method. The dictionary may be empty, or 
> it may contain a variable number of items, and it may contain items not 
> looked for by the setup() method. Moreover, this method may be 
> overridden in subclasses. The approach described above works ok, so I 
> suppose I should leave well enough alone, but I have this nagging 
> feeling that Python has a way to do this more simply or more elegantly. 
> Any suggestion?

  One possibility is to split the work into many methods:

    def setup(self, items={}):
        for k, v in items.itervalues():
            fName = "setup_" + k
            fObj = getattr(self, fName, None)
            if fObj is not None:
                fObj(v)

    def setup_eggs(self, value):
        # ...

    def setup_spam(self, value):
        # ...

  Jp