Python function in function

Question

def example(function):
    if input() == "Hello there!":
        #at this point I want to call the function entered in the tuples

an example of what I mean:

def example(function):
    if input() == "Hello there!":
        #do the function here

def Printer(What_to_print):
    print(What_to_print + "Just an example")


example(Printer)

Is this possibe and are there drawbacks in doing this?

Do you mean passing function as an argument to another function? Yes, it is possible and is quite common. — bereal, Aug 13 '16 at 18:42
It isn't just possible. [Several](https://docs.python.org/3/library/functions.html#map) built-in [functions](https://docs.python.org/3/library/functions.html#filter) take [functions](https://docs.python.org/3/library/functions.html#classmethod) as [arguments](https://docs.python.org/3/library/functions.html#staticmethod). — zondo, Aug 13 '16 at 19:36
Those things the function's `function` argument is between are called [parentheses](http://www.dictionary.com/browse/parentheses). A [`tuple`](https://docs.python.org/3/library/stdtypes.html#tuple) is a built-in Python sequence type whose construction can look very similar. — martineau, Aug 13 '16 at 20:15

score 0 · Answer 1 · answered Aug 13 '16 at 19:10

In python, functions are objects like any other common types, like ints and strs. Therefore, there is no problem with a function that receives another function as an argument.

>>> def pr(): print ('yay')

>>> def func(f): f()

>>> isinstance(pr, object)
True
>>> isinstance(int, object)
True
>>> func(pr)
yay
>>>

frogatto · Accepted Answer · 2016-08-13T19:57:53.180

0

Yes. It is possible.

def example(function):
    if input() == "Hello there!":
        function("Hello there!")  # invoke it!

Actually you can pass def functions and lambda functions as parameters and invoke them by () syntax.

edited Aug 13 '16 at 19:57

answered Aug 13 '16 at 19:15

frogatto

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Sorry for asking this (i'm really new to coding) but could you give me an example of what you mean by invoking it? – Andreas Sandberg Aug 13 '16 at 19:20
@AndreasSandberg By invoking, I mean calling the function. In your words, _doing_ the function. – frogatto Aug 13 '16 at 19:20
I probaly sound really stupid right now, but I don't know what to add after the ; and when I remove it the `example` prints what I want it to print without me doing anything, and when I type in Hello there! I just get lots of errors. – Andreas Sandberg Aug 13 '16 at 19:43
@AndreasSandberg Sorry, my bad! Python doesn't need semicolons. updated my answer. – frogatto Aug 13 '16 at 19:45
this when ran just calls the function in it without me having to type Hello there! and when I type Hello there! it says TypeError: 'NoneType' object is not callable – Andreas Sandberg Aug 13 '16 at 19:51
@AndreasSandberg updated my answer again. You can simply pass all needed parameters to the function being called as it would in regular functions calls. – frogatto Aug 13 '16 at 19:59

score 0 · Answer 3 · answered Aug 13 '16 at 19:28

0

def example(function, what_to_print):
    if raw_input() == "Hello there!":
        function(what_to_print)

def printer(what_to_print):
    print(what_to_print + "Just an example")

example(printer, "")

answered Aug 13 '16 at 19:28

cridnirk

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Python function in function

3 Answers3