To begin with: what are these mystical creatures? Well, let me break it down for you in a way that even your grandma could understand.

Finalizers (also known as destructors) are functions or methods called when an object is intended to be disposed of. They can access the object and release any resources held by the object (for example mutexes or file descriptors). An example is a __del__ method.

Wait, what’s that? A __del__ method? Yes, bro! It’s a special method in Python classes that gets called when an instance of that class is about to be destroyed. This can happen for various reasons: the object goes out of scope, it’s assigned to another variable or its reference count reaches zero (which happens automatically when there are no more references to the object).

Now, you might ask yourself: “Why do we need finalizers and __del__() methods in Python if we have a garbage collector that handles memory management for us?” Well, bro, that’s a great question! And here’s your answer: sometimes, you want to perform some cleanup operations when an object is destroyed. For example, closing a file or releasing a lock on a resource.

There are some important differences between finalizers and __del__() methods that you should be aware of. First, finalizers can create new references to the object they’re called for (which is known as “object resurrection”). This can happen if the finalizer creates a new reference to the object in its body. However, this behavior is not recommended and it’s implementation-dependent whether __del__() methods are called again when an object is resurrected.

Secondly, there’s no guarantee that __del__() methods will be called for objects that still exist when the interpreter exits. This means that you can’t rely on them to perform cleanup operations in all cases. Instead, it’s better to use context managers or other techniques to ensure proper resource management.

Finally, there are some implementation details that you should be aware of if you want to write your own finalizers and __del__() methods. For example:
– If a base class has a __del__() method, the derived class’s __del__() method must explicitly call it to ensure proper deletion of the base class part of the instance.
– The reference count of an object is decremented when a variable goes out of scope or its value changes (e.g. if you assign a new value to a variable that previously held a reference to an object). This can cause the object’s __del__() method to be called automatically, even if there are still references to it elsewhere in your program.
– The order in which finalizers and __del__() methods are called is not guaranteed (except for objects created with the ctypes module or other C extensions that use reference counting). This means that you can’t rely on them to perform cleanup operations in a specific order.

That’s it! Finalizers vs __del__() methods: a tale of two beasts. Remember, always use context managers and other techniques for proper resource management instead of relying solely on finalizers or __del__() methods. And if you’re feeling adventurous, try writing your own destructor method and see what happens!