Add a function as a parameter in Python-CodePudding

Imagine that I want to create a function called "execute()". This function takes the name of another function and its input as parameters and outputs whatever it returns.

Here is an example:

execute(print, "Hello, World!") # "Hello, World!"
execute(str, 68) # "68"

Of course, this function wouldn't be of any use, but I want to grasp the main idea of putting another function in as a parameter. How could I do this?

CodePudding user response：

You can just do this,

def execute (func, argv):
    return func(argv)

execute(print, 'test')

returns test

execute(str, 65)

returns '65'

CodePudding user response：

Functions can easily be passed into functions. To pass a variable length argument list, capture it with *args in the function definition and when calling the func use the same syntax to expand the arguments again into multiple parameters.

def execute(fn, *args):
  return fn(*args)

Note: we are not passing the name of a function to execute(), we are passing the function itself.

CodePudding user response：

I believe this should work:

def execute(fn, *args, **kwargs):
    return fn(*args, **kwargs)

Here:

args = Arguments (list)
kwargs = Keyworded Arguments (dictionary)

If you want to do more, then you can look for Decorators in Python.

CodePudding user response：

Yes, you can pass functions as parameters into another function. Functions that can accept other functions as arguments are also called higher-order functions. I hope the following example helps:

def shout(text): 
    return text.upper() 

def greet(func):
   greeting = func("Hi, I am created by a function passed as an argument.") 
   print(greeting)

greet(shout)

The output of the code will be :

HI, I AM CREATED BY A FUNCTION PASSED AS AN ARGUMENT.