Posts tagged decorators

Decorators: Reinventing the Wheel

Hey everyone, welcome to another week of Camerons Corner! This is going to be my last post on decorators for a little while, so I wanted to take some time and expand on what packages you might see generators in and how I would implement them if I had to from scratch. In this post, I’m going to reinvent the wheel- that is you’ll see code I’ve written to replicate popular decorators from many third party packages. I am aiming to replicate only the core functionality of these decorator patterns in order to better highlight that these mechanisms are not something magical. There is real code underlying these patterns that enable unique design patterns.

When writing these examples, I only looked at various documentation pages & examples that use these decorators. No source code was examined or copied.

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Python: Advanced Decorators

In a previous post, I shared a primer on how to approach the thinking of decorators and when we can apply them in our code. To summarize, we primarily see 3 entry points where decorators can dynamically effect our code:

entry point

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Python: Decorator Fundamentals

Python has had the standard @decorator style decorator syntax since PEP 318 – Decorators for Functions and Methods was accepted, while some tweaks to the grammar have been made a long the way via PEP 3129 – Class Decorators and PEP 614 – Relaxing Grammar Restrictions On Decorators, their behavior has remained largely unchanged.

The most common misconception about decorators is that they are a function that takes a function and returns a function. While this does describe a common pattern for decorators, it ignores their generalized framework and misses strong usecases for decorators. Instead, I will say that a decorator is a callable that takes a class or function as an argument to encapsulate/manipulate some state and/or prepend/append some behavior to that class or function. While that definition is quite verbose, I think the following code snippets will help make my point.

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