Thorsten Kampe wrote:
> [Crossposted to tutor and general mailing list]
>
> Hi,
>
> I'd like to extend the dictionary class by creating a class that acts
> like a dictionary if the class is instantiated with a dictionary and
> acts like a "dictitem" ([(key1, value1), (key2, value2), ...]) if
> instantiated with a list (that is dictitem).
>
> The code (see extract at bottom) works well but it contains a lot of
> "if this is a dictionary then do as a dictionary already does"
> boilerplate code". How can I "inherit"(?)/"subclass"(?)/derive from
> dict so I don't have to write the code for the dictionary case?
Hm.
def GenericDict(dict_or_items):
if isinstance(dict_or_items, dict):
return dict(dict_or_items)
else:
return SimpleGenericDictWithOnlyTheFalseBranchesImplemented(
dict_or_items
)
>
> Thorsten
>
> ```
> class GenericDict:
> """
> a GenericDict is a dictionary or a list of tuples (when the keys
> are not hashable)
> """
> def __init__(inst, generic_dict):
> inst._generic = generic_dict
>
> def __getitem__(inst, key):
> if isinstance(inst._generic, dict):
> return inst._generic[key]
> else:
> return inst.values()[inst.keys().index(key)]
It's not obvious why you'd ever want that. What's the use case?
If you have unhashable keys consider bisect...
> def values(inst):
> if isinstance(inst._generic, dict):
> return inst._generic.values()
> else:
> try:
> return list(zip(*inst._generic))[1]
> except IndexError: # empty GenericDict
> return ()
>
> def keys(inst):
> if isinstance(inst._generic, dict):
> return inst._generic.keys()
> else:
> try:
> return list(zip(*inst._generic))[0]
> except IndexError: # empty GenericDict
> return ()
> ```
--
https://mail.python.org/mailman/listinfo/python-list
