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Editor to share with you how to achieve Python return function + anonymous function, I hope you will learn something after reading this article, let's discuss it together!

Return function

After a rough look at the learning materials, I feel that the meaning of the return function is easy to understand, but it is a bit troublesome in practical application.

Let's get this straight.

First of all, the higher-order function can not only accept the function as a parameter, but also return the function as a result value.

Function as a return value

Take the sum as a simple example:

The general summation function would be written as follows:

> def calc_sum (* args):

A = 0

For n in args:

A = a + n

Return a

> calc_sum (1, 2, 3, 4)

ten

Solve the problem directly and return the result.

But sometimes we don't need to sum right away, maybe we need to calculate later, and then we need to use the return function.

When I see this, all I can think about is: why not make peace right away? )

What exactly is the function of the return function?

It's like doing something, and in the process of doing it, the function of the return function is to tell you where / how I've done it and what you can do.

There is no more specific example for the time being. I hope I can encounter it in the future and deepen my understanding. It's too abstract! )

OK, let's go back and see how to write the sum with the return function.

(instead of returning the summation result, it returns a summation function)

> def lazy_sum (* args):

Def sum ():

A = 0

For n in args:

A = a + n

Return a

Return sum

> f = lazy_sum (1, 3, 5, 7, 9)

> > f

As you can see, when we call lazy_sum (), instead of returning the sum result, we return the sum function.

If you want to calculate the real sum result, you need to call f. [f () equals sum ()]

> > f ()

twenty-five

The inner function sum can refer to the parameters and local variables of the external function lazy_sum.

When lazy_sum returns the function sum, the relevant parameters and variables are saved in the returned function. Although this is a very easy to understand sentence, but I somehow feel that it is not simple!

This kind of program structure is called Closure. (roar!

It is important to note that each time you call lazy_sum, a new function is returned!

Even if the input parameters are the same, the returned function is different!

F1 = lazy_sum (1, 3, 5, 7, 9)

> f2 = lazy_sum (1,3,5,7,9)

> f1==f2

False

The call results of (F1 () and f2 ()) do not affect each other.

After reading this article, I believe you have a certain understanding of "how to realize the return function + anonymous function in Python". If you want to know more about it, please follow the industry information channel. Thank you for reading!

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