A detailed explanation of function scopes and anonymous functions

A detailed explanation of function scopes and anonymous functions

1. Function scope

In programming, scope is a very important concept that determines the accessibility of variables, functions, and objects. Function scope mainly refers to the variables and functions defined inside the function can only be accessed inside the function, but not outside the function.

Local scope: A variable or function defined inside a function that has a local scope. These variables or functions can only be accessed inside the function, and when the function is executed, they no longer exist.

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Global scope: A variable or function defined outside of a function that has a global scope. These variables or functions can be accessed anywhere in the program.

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Nested scopes: Another function or variable defined inside a function has a nested scope. These variables or functions can be accessed inside nested functions, but not in external functions or global scopes.

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2. Anonymous functions

An anonymous function, also known as a lambda function, is a function that has no name. It's typically used when you need a function as an argument, but don't want to define a formal function. Lambda functions are used in PythonlambdaThe keyword is defined with the following syntax:

Python reproduces Lambda Arguments: Expression

expressionis a single expression, and the value returned by the lambda function is the result of this expression.

For example, define an anonymous function that takes two arguments and returns their sum:

python copy **add = lambda x, y: x + yprint(add(3, 4)) output: 7

Summary

Function scopes determine the accessibility of variables and functions, while anonymous functions provide a concise way to define simple functions. Understanding these concepts is important for writing clear, effective **.