In this article I talked about how to pass a function to a variable, nested functions, returning functions, and passing a function to another function as an argument. This class will keep track of the state of the class. '''Log the date and time of a function''' This decorator logs the date and time a function is executed: from datetime import datetime You prefix the decorator function with an symbol. We use a decorator by placing the name of the decorator directly above the function we want to use it on.
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To use a decorator ,you attach it to a function like you see in the code below. Here is the syntax for a basic Python decorator: def my_decorator_func(func): There is also an inner function that wraps around the decorated function. To create a decorator function in Python, I create an outer function that takes a function as an argument. I am going to the store buy you something nice. # Calling the friendly_reminder function with the action function used as an argument. Print('I am going to the store buy you something nice.') Print('Don\'t forget to bring your wallet!') A function can be passed to another function as an argument.
Since a function can be nested inside another function it can also be returned. NameError: name 'inner_function' is not definedģ. If I try to execute the inner_function outside of the outer_function I receive a NameError exception. Note that the inner_function is not available outside the outer_function. # Executing the inner function inside the outer function. A function can be nested within another function. We don't want to execute the function.ĭescription = my_function # Accessing the function from the variable I assigned it to.Ģ. # Assign the function to a variable without parenthesis. The function can be accessed from that variable. Because of that, a function can be assigned to a variable. To get a better understanding of how decorators work, you should understand a few concepts first. Here are the building blocks used to create Python decorators This avoids you writing duplicating code. You can also use one when you need to run the same code on multiple functions.
A few good examples are when you want to add logging, test performance, perform caching, verify permissions, and so on. You'll use a decorator when you need to change the behavior of a function without modifying the function itself. Real-world examples of Python decorators.Building blocks you use to create a decorator.In this article I will discuss the following topics: You will see how easy it is to use this advanced Python feature. In this article I will show you how to create and use decorators. Python decorators allow you to change the behavior of a function without modifying the function itself.
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