heya,
Dave: Ahah, thanks =).
You're right, my terminology was off, I want to dynamically *instantiate*, not
create new classes.
And yes, removing the brackets worked =).
Cheers,
Victor
On Monday, 10 December 2012 11:53:30 UTC+11, Dave Angel wrote:
> On 12/09/2012 07:35 PM, Victor Hooi wrote:
>
> > Hi,
>
> >
>
> > I have a directory tree with various XML configuration files.
>
> >
>
> > I then have separate classes for each type, which all inherit from a base.
> > E.g.
>
> >
>
> > class AnimalConfigurationParser:
>
> > ...
>
> >
>
> > class DogConfigurationParser(AnimalConfigurationParser):
>
> > ...
>
> >
>
> > class CatConfigurationParser(AnimalConfigurationParser):
>
> > ....
>
> >
>
> > I can identify the type of configuration file from the root XML tag.
>
> >
>
> > I'd like to walk through the directory tree, and create different objects
> > based on the type of configuration file:
>
> >
>
> > for root, dirs, files in os.walk('./'):
>
> > for file in files:
>
> > if file.startswith('ml') and file.endswith('.xml') and 'entity'
> > not in file:
>
> > with open(os.path.join(root, file), 'r') as f:
>
> > try:
>
> > tree = etree.parse(f)
>
> > root = tree.getroot()
>
> > print(f.name)
>
> > print(root.tag)
>
> > # Do something to create the appropriate type of
> > parser
>
> > except xml.parsers.expat.ExpatError as e:
>
> > print('Unable to parse file {0} -
> > {1}'.format(f.name, e.message))
>
> >
>
> > I have a dict with the root tags - I was thinking of mapping these directly
> > to the functions - however, I'm not sure if that's the right way to do it?
> > Is there a more Pythonic way of doing this?
>
> >
>
> > root_tags = {
>
> > 'DogRootTag': DogConfigurationParser(),
>
> > 'CatRootTag': CatConfigurationParser(),
>
> > }
>
> >
>
> > Cheers,
>
> > Victor
>
>
>
> Your subject line says you want to create the classes dynamically, but
>
> that's not what your code implies. if you just want to decide which
>
> class to INSTANTIATE dynamically, that's easily done, and you have it
>
> almost right. In your dict you should leave off those parentheses.
>
>
>
>
>
>
>
> Then the parser creation looks something like:
>
> parser_instance = root_tags[root.tag] (arg1, arg2)
>
>
>
> where the arg1, arg2 are whatever arguments the __init__ of these
>
> classes expects.
>
>
>
> (untested)
>
>
>
> --
>
>
>
> DaveA
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