Does Python have an equivalent to 'switch'?

Question

I am trying to check each index in an 8 digit binary string. If it is '0' then it is 'OFF' otherwise its 'ON'.

Is there a more concise way to write this code with a switch-like feature.?

Answer 1

No it doesn't. When it comes to the language itself, one of the core Python principles is to only have one way to do something. The switch is redundant to:

if x == 1:
    pass
elif x == 5:
    pass
elif x == 10:
    pass

(without the fall-through, of course).

The switch was originally introduced as a compiler optimization for C. Modern compilers no longer need these hints to optimize this sort of logic statement.

Answer 2

Try this instead:

def on_function(*args, **kwargs):
    # do something

def off_function(*args, **kwargs):
    # do something

function_dict = { '0' : off_function, '1' : on_function }

for ch in binary_string:
   function_dict[ch]()

Or you could use a list comprehension or generator expression if your functions return values:

result_list = [function_dict[ch]() for ch in binary_string]

Answer 3

else-if is bad practice, since they are unsafe when they get too long, and involve unnecessary conditional branching (maybe affecting compiler / caching).

try this...

class Functions():
    @staticmethod
    def func():
        print("so - foo")
    @staticmethod
    def funcWithArgs( junk ):
        print(junk, "foo")

# fill in your cases here...
cases = {
    "a" : Functions.func ,
    "b" : Functions.funcWithArgs ,
    "c" : Functions.funcWithArgs
}

def switch( ch, cases, *args ):
    try:
        len(*args)  # empty args
    except TypeError:
        return cases[ ch ]( )
    return cases[ ch ]( *args )

# try out your switch...
switch("a", cases)  # "so - foo"
switch("b", cases, "b -")  # "b - foo"
switch("c", cases, "c -")  # "c - foo"