[Python-Dev] Is X a (sequence|mapping)?

[Ka-Ping Yee]

We can implement abstract interfaces (sequence, mapping, number) in
Python with the appropriate __special__ methods, but i don't see an
easy way to test if something supports one of these abstract interfaces
in Python.

At the moment, to see if something is a sequence i believe i have to
say something like

    try:
        x[0]
    except:
        # not a sequence
    else:
        # okay, it's a sequence

or

    if hasattr(x, '__getitem__') or type(x) in [type(()), type([])]:
        ...

Is there, or should there be, a better way to do this?



-- ?!ng