[Python-Dev] Simple Switch statement

[Raymond Hettinger]

[Phillip Eby]
> I would like to be able to use switches on types, enumerations, and the like.

Be careful about wanting everything and getting nothing.
My proposal is the simplest thing that gets the job done for key use cases found 
in real code.
Also, it is defined tightly enough to allow room for growth and elaboration over 
time.
Good luck proposing some alternative that is explainable, has no hidden 
surprises,
has an easy implementation, and allows fast hash-table style dispatch.
Besides, if you want to switch on other types, it is trivial to include a 
reverse mapping
(like that in the opcode.py example).  Reverse mappings are to build and easy to 
read:


# enumeration example
colormap = {}
for code, name in enumerate('RED ORANGE YELLOW GREEN BLUE INDIGO 
MAGENTA'.split()):
    globals()[name] = code
    colormap[code] = name

def colormixer(color):
    switch colorname[color]:
        case 'RED', 'YELLOW', 'BLUE':
            handle_primary()
        case 'MAGENTA':
            get_another_color()
        default:
            handle_rest()


colormixer(RED)
colormixer(ORANGE)



Raymond