Python is wierd!

[Alex Martelli]

"David Bolen" <db3l at fitlinxx.com> wrote in message
news:u7la8m8ir.fsf at ctwd0143.fitlinxx.com...
    [snip]
> If I'm going to package up some state (various bits of information)
> into a class (aka using one as a structure - data only), one approach
    [snip]
>     class MyInfo:
>         def __init__(self):
>             self.variable = initial_value
>             self.other_variable = initial_value
    [snip]
> I'm curious what others would think of the two approaches?

My instinct (and, again, since my Python experience is limited, it is
quite possible that my instinct is off-base!) would be to enrich the
second approach.  If I'm "just packaging data", client code will
often want to give non-default initial values to one or more fields,
so, why not make it convenient.

If I have a good grasp on what fields will be actually used, then...:

class MyInfo:
    def __init__(self, variable=None, other_variable=None):
        self.variable = variable
        self.other_variable = other_variable


If I don't really know what fields client-code will want to pack into
the structure, then...:

class MyInfo:
    def __init__(self, **fields):
        self.__dict__.update(fields)


In either case, a __getdict__ can also be a valuable adjunct
to turn name-errors into automagically-initialized fields (or, it
can be a "pitiful crutch", a lazy prop to avoid designing it right
in the first place -- depending on how keen one is towards
up-front design versus a more exploratory style:-).


Alex