I have a code in which the user chooses the function he wants to execute. There is no definite amount of functions as the functions may increase in the future. I am storing the value fetched from the User input into a variable. I want to make the variable callable.
functions = ['add','sub','mul']
a = 10
b = 5
x = input('Choose a function : ')
def add():
print(a+b)
def mul():
print(a*b)
def sub():
print(a-b)
x()
I want the variable 'x' to be called and executed as a function.
I think, correct solution for this will be dict. Also it gives you some flexibility to give different string keywords for functions. Code:
def add(a, b):
print(a + b)
def mul(a, b):
print(a * b)
def sub(a, b):
print(a - b)
functions = {
'add': add,
'sub': sub,
'mul': mul
}
a = 10
b = 5
x = input('Choose a function : ')
if x not in functions:
print(f"Function \"{x}\" is not defined.")
else:
functions[x](a, b)
But if you think that it's 100% neccesary to call function by string name, you can get reference to function from globals():
func = globals().get(x, None)
if not x:
print(f"Function \"{x}\" is not defined.")
else:
func(a, b)
eval() could work for you, just know that it allows arbitrary code execution, so be careful how you allow values to get passed to it.
E.g.:
$ python
Python 3.7.2 (default, Feb 12 2019, 08:15:36)
[Clang 10.0.0 (clang-1000.11.45.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> def a():
... print('a')
...
>>> def b():
... print('b')
...
>>> func = eval('a')
>>> func()
a
>>> func = eval('b')
>>> func()
b
>>>
Or with the user selection step:
# ...
>>> func_choice = input('Choose a function: ')
Choose a function: a
>>> func = eval(func_choice)
>>> func()
a
>>>
eval.
eval(func_name) with globals()[func_name]() which will be more "secure".I notice you don't use functions, but you're on to something there. It should be a dictionary of names to functions
def add():
...
functions = {'add': add,'sub': sub, 'mul': mul}
choice = input('Choose a function : ')
f = functions[choice]
f()
x=addThen you can call x as a function.x(1,2)