dsandler.org/wp

There’s a fun thread over here about the different idioms
people use to approximate C switch in Python (which has no
equivalent keyword). I love the delicious functional-programming flavor
of the author’s original suggestion:

ref="http://simon.incutio.com/archive/2004/05/07/switch">

result = {
  'a': lambda x: x * 5,
  'b': lambda x: x + 7,
  'c': lambda x: x - 2
}[value](x)

However, I frequently need a little more oomph than you can fit
in Python’s anemic lambda construct. I find myself using
the following idiom, which allows me to do tricky C switch
things like fall through from one case to another:

for value in [value]:
  if value == 'a':
    result = x * 5
    break
  if value == 'b':
    result = x + 7
    break
  if value == 'c':
    result = x - 2
    break
  # default
  result = x
  break

OK, that first line is a little contrived, but there’s typically something more complex than [value] up there on the first line. I’m often testing the result of a more complex expression (like switch(expr) in C) so it’s useful to capture that computation once.

It doesn’t quite fall through like C switch (the test you fall into still has to succeed). But, hey, it does use the break keyword.