A simple function (roughly) implementing C-style switch statements.

switch.py

"""A simple function (roughly) implementing C-style switch statements.

Usage::
    switch(value, {
        'it':
            "You said the word!",
        
        'fruit':
            "Suppose he's got a pointed stick.",
        
        'camelot':
            "'Tis a silly place.",
        
        Ellipsis:
            ("You've got two empty halves of coconut and you're " +
             "bangin' 'em together.")
    })

Also accepts *args and **kwargs, which will get passed on to the
specified case if it is callable.

The result of the callable is returned, as is the value of
non-callables.

Since `default` isn't a built-in name (and obviously not a statement),
the under-used  built-in singleton Ellipsis is used in its place under
the assumption that it is unlikely to be used as a real case.

Fortunately, in the event that it *is* used as a real case, using
Ellipsis as the switch value will properly select the Ellipsis case.
Unfortunately, so will a non-match. It's probably best you don't use
Ellipse as a real case.

Finally: implicit break, no fall-through at all. Ever. First of all,
dict isn't ordered, so fall-through would be weird. Second, I'm not
going to specialize for OrderedDict (plus it would look weird on your
end), and third, I have no idea how to put breaking in if I did. If you
want this, do it yourself.

"""

def switch(value, cases, *args, **kwargs):
    try:
        case = cases[value]
    except TypeError:
        raise TypeError("Cases must be scriptable.")
    except KeyError:
        case = cases[Ellipsis] if Ellipsis in cases else None
    finally:
        try:
            return case(*args, **kwargs)
        except TypeError:
            return case

def main():
    import sys
    try:
        value = sys.argv[1]
    except IndexError:
        value = None
    
    print switch(value, {
        'it':
            "You said the word!",
        
        'fruit':
            "Suppose he's got a pointed stick.",
        
        'camelot':
            "'Tis a silly place.",
        
        Ellipsis:
            ("You've got two empty halves of coconut and you're " +
             "bangin' 'em together.")
    })

if __name__ == "__main__":
    main()