python - Expressions in a dictionary mapping -

i have series of conditionals of form:

if ':' in particle:     elif 'eq' in particle:       else elif 'lt' in particle:     thing elif 'le' in particle:     etc. elif 'gt' in particle:     etc., etc. elif 'ge' in particle:     etc., etc., etc. elif 'ne' in particle:     more etc. 

i want implement using dictionary mapping pattern, having issues keys.

i tried this:

def case_evaluator(particle):     switcher = {         ':' in particle: something,         'eq' in particle: else,         'lt' in particle: thing,         ...     }     return switcher.get(particle, "nothing") 

but, kept getting "nothing." how can give nothing?

this seems should simple, alas...

you want have dictionary maps characters functions.

char_function_dict = {     ':': colon_function,     'eq': eq_function,     'lt': lt_function     # ...and on... } 

then, can iterate on key-value pairs in dictionary.

def apply_function(particle):     char, function in char_function_dict.items():         if char in particle:             function() 

however, note structure doesn't use specific dictionaries , doesn't preserve order characters checked. perhaps more simple use list of 2-element tuples.

char_functions = [     (':', colon_function),     ('eq', eq_function),     ('lt', lt_function)     # ...and on... ]  def apply_function(particle):     char, function in char_functions:         if char in particle:             function()             break # successive functions not run 

setting either of these structures allow arguments and/or keyword arguments passed functions easy:

def apply_function(particle, *args, **kwargs):     char, function in char_functions:         if char in particle:             function(*args, **kwargs)             break