Explaining monkey patching in Python with simple examples so that everyone can understand. In this tutorial, I will mention its use-case where you can use it in your project or program.

Often, when programming, we may want to change some already set behavior. This can be accomplished by sub-classing whatever classes we have and overriding those methods we are not happy with.class. Since Python 3.8, AsyncMock. Unfortunately datetime.date is written in C, and so I couldn’t just monkey-patch out the static date.today method. Python Patch Decorator Approach #1 – Simple replacement. The first approach is simple and you’ll likely have many use cases for it. We are going to configure the decorator to target the school api and give it a method to replace the real API call. The first argument to patch will be the lookup path of the api method. This will be the same imported path used in your class under test.

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What is Monkey Patching?

Monkey patching is a dynamic technique in Python by which you can modify the behavior of an existing class or module.

To change the behavior of class or module, you don’t need to change the code inside class or method.

Let’s see how you can do that.

I’m taking two coding examples to change the behavior of the class and module.

Example: Monkey Patching Python Class

Python Program To Change the behavior of Class Dynamically:

Output:

In the above program, we have created an instance objMonkey of class monkey.

We are assigning a new method name (patchFunc) to the existing class method name (monkeyFunc). The linking of a new method to the existing class method name happens at runtime. So the behavior of the class monkey is changed dynamically.

In the above class, you are changing the behavior of the class method defined in the same program file.

Now let’s take another example of a monkey patching Python module.

Example: Monkey Ptaging Python Module

Write your own modules called animals.

Save this file as animals.py
Now import this file as Python module in your another Python program.

Output:

Python Monkey Patch Static Method Tutorial

We are getting the same output. This time we have changed the behavior of the method defined inside the module animals without changing a single line of code inside the animals.py.

Python Monkey Patch Static Method Template

In this example, I tried the monkey patching my own module. Similarly, you can try it on existing standard modules.

[Use-Case] What’s the use of monkey patching?

Python Static Method Call

Let’s take an example.

Suppose you are importing the standard module. Modules have different methods.

As per your requirement, you want the method inside the module to work differently. It’s not easy to go to the method defined inside the standard module and change it.

The simplest way of doing the same things is by monkey patching technique.

How does it work?

You write your own method.
Assign this method name to the method name defined inside the module.
Now every time when you call the method defined inside the module, it calls your own method.

You changed the behavior of the method defined in the module.

Download naruto shippuden eps 1-500 sub indo mp4 indonesia. Conclusion

This is all about monkey patching in Python- a technique to change the behavior of class or module.

There is also another technique called decorators in Python to change the behavior of code without changing the actual code dynamically.

Monkey patching is a technique to modify module functions or class methods in Python and other dynamic languages run-time. It differs from the traditional source code patching that it does not need separate utility or compilation process to become effective. This means that you can deploy patches to codebase not under your control with your application without extra effort. Monkey patching has been made famous by Plone/Zope community where there is even collective.monkeypatcher add-on for managed monkey patching.

Because monkey patches do not need a compilation stage, the patch will work with the future versions of the application, assuming the patched function or method is not changed. So you can “safely” update the patched software and the patch will apply to the new version without need to go to command-line to perform some cumbersome commands. However, it is the best practice of open source community to report the bugs and submit the fixing patches, as source code patch, in the corresponding issue trackers.

In Django context, you can use monkey patching to

Fix bugs or modify features of Django core without touching the source code
Fix bugs or modify features of Django plug-ins (TinyMCE, filebrowser, Django CMS) without touching the source code

Patches are usually applied when Python does module imports. You have a special module called “monkeypatches.py” and when that is imported, it applies the patches when the module body level code runs. However, it is difficult to find stable import point in Django to run monkey patching. Django does some really evil magic to initialize INSTALLED_APPS, database models and stuff and doing any kind of work during import causes headache.

Python Monkey Patch

So I figured out that you can apply monkey patches using middleware. Middleware applies the monkey patch when the first HTTP request hits the process (note that if you run preforked web server like FCGI every process has its own run-time code in memory). This technique, of course, cannot be used to monkey-patch things that happen before middleware processing, but it is not often needed.

Below is an example how to monkey-patch Django CMS to normalize its unicode output. Download game marc ecko getting up under pressure pc case. There was an issue with unicode characters and this is a stop-gap measure to fix it. (I think the proper fix would be fix related Cufon font renderin Javascript library).

We add our monkey patcher to loaded middleware in settings.py.

The actual monkey patching happens by fiddling with the class code in process_request(). Note that in this particular case we only need to transform the output of the original function, we can simply hold a reference into it, call it and perform our transformation on the result. This way our monkey patch do not hinder the orignal function and is update safe (it does not matter if the code of PlaceholderNode.render method changes).

As far as I know, monkey patching is something PHP cannot do 🙂