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How can functions be parameters for other functions?

all I can say is "wow"! functions calling functions; cats and dogs sleeping together; "wow"!

5th Mar 2017, 12:34 AM
John Myers
John Myers - avatar
5 ответов
+ 6
If a function returns a value, you can use it like a value. Here's an example: value = sum(double(5), double(3)) First, double(5) is run, which returns 10. Then, double(3) is run, and returns 6. So then sum() works with those returned numbers: sum(10, 6) and returns 16. Pretty neat!
5th Mar 2017, 1:04 AM
Tamra
Tamra - avatar
+ 6
you can also return a function as value: def f1(x): return x*5 def f2(x): return x+2 c = 0 def test(): global c c = (c+1)&1 return f1 if c else f2 for i in range(5): f = test() print(f(i))
6th Mar 2017, 7:26 AM
visph
visph - avatar
+ 2
One more common instance of a function calling a function is a recursive function, which repeatedly calls the function over and over until the function calls the base case and ends. I have seen recursive functions where the programmer either had no base case or wrote a base case that would never be called, resulting in an outcome that would be considered bad.
7th Mar 2017, 11:56 PM
Frederick Eccher
Frederick Eccher - avatar
+ 1
A function can be input to a higher order function. For instance, you want to know if an element x of an iterable I verifies the function F(x) == True, you can do it in the following way: def exists(F, I): for x in I: if F(x): return True return False
5th Mar 2017, 10:57 PM
Amaras A
Amaras A - avatar
0
Thanks for your insights!
5th Mar 2017, 1:23 AM
John Myers
John Myers - avatar