This doesn't not intent to be nor became a standard. Instead it's thought to be a proof of concept for a construction which mimics switch/case statements. I think it's funny, so, i'll hope you enjoy it as I do.
Python, 59 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 | from __future__ import with_statement
from contextlib import contextmanager
@contextmanager
def Switch():
D = {}
class _P(Exception): pass
def _mkCase(var):
class _PP(_P):
V = var
def __repr__(self):
return str(self.V)
D[var]=_PP
return _PP
def switch(var):
if D.has_key(var):
raise D[var]()
raise _mkCase(var)()
def case(var):
if D.has_key(var):
return D[var]
return _mkCase(var)
def default():
return _P
yield switch, case, default
if __name__=="__main__":
def test1():
with Switch() as (switch, case, default):
try: switch(55)
except case(1):
print 1
except case(6):
print 6
except case(5):
print 5
except default():
print 'default..'
def test2():
with Switch() as (switch, case, default):
try:switch('hola')
except case(1):
print 1
except case('holaS'):
print 'holaS'
except case('hola'):
print 'hola'
except default():
print 'default..'
test1()
test2()
|
Discussion is open :-)
Whats wrong with using dictionaries instead of Exceptions. Using exceptions to implement a switch syntax seems to be a misuse of exceptions to me. I always thought dictionaries are the way to go:
Whats wrong with using dictionaries instead of Exceptions. There's nothing wrong.
That's the way to do kind-of switch, other way is to have something polymorphic.
I've made as an exercise.
Functions! I've found that functions are typically replaced with a None in a dictionary. This seems to be the only way to get around it.