Using a function as dictionary key

Question

Is it considered bad form to use a function as a dictionary key? For example:

def add(a, b):
    return a + b

mydict = {add: "hello"}

Answer 1

Yes, that's perfectly valid. You could for instance use it to store a counter to how many times a function was called:

def hi():
    print('hi')

funcs = {hi: 0}

print(funcs)
# {<function hi at 0x10fb39950>: 0}

for func in funcs:
    func()
    # hi
    funcs[func] += 1

print(funcs)
# {<function hi at 0x10fb39950>: 1}