Generic dictionary

[Thorsten Kampe]

[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?

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)]

    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 ()
```