On Thu, 23 Sep 2010 06:07:21 am Pete wrote:
> For a plugin mechanism, I'm populating a dict with calls to the
> implemented plugins.
[...]
> Now I get that I need to instantiate foo and bar first before I can
> refer to them in the dict.
>
> so something like
>
> foo_instance = foo()
> bar_instance = bar()
>
> list = { 'foo': foo_instance.do(), 'bar': bar_instance.do() }
>
> would probably work. But is that the best/pythonic way to do it?
(1) It's generally a bad idea to "shadow" the name of a built-in
function like list. Particularly since your variable list isn't
actually a list, but a mapping of name:function. Find a better
name :)
(2) You end up calling the do() methods inside the dict. You probably
mean to save the method itself as a callback function.
(3) There's no need to keep the instances floating around as
independent names, unless you need direct access to them.
Putting these together, we get:
dispatch_table = { 'foo': foo().do, 'bar': bar().do }
Which you then later call using:
dispatch_table[name](args)
where name is "foo" or "bar", and args is anything you need to pass to
the do() method.
Oh, and (4)... in Python circles, it's traditional but not compulsory
to use metasyntactic variables named after Monty Python sketches
rather than foo and bar. So spam, ham, eggs, parrot (dead or
otherwise), names of cheeses, aardvark..., although there is no
standard order.
Indeed, when I design my killer language, the identifiers "foo" and
"bar" will be reserved words, never used, and not even mentioned in
the reference manual. Any program using one will simply dump core
without comment. Multitudes will rejoice. -- Tim Peters, 29 Apr 1998
--
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