Python’s magic method __getattribute__() implements the built-in getattr() function that returns the value associated with a given attribute name. If the __getattribute__() error results in an AttributeError due to a non-existent attribute, Python will call the __getattr__() function for resolution. Thus, the __getattribute__() method takes precedence over the __getattr__() method. We call this a “Dunder … Read more
Python’s magic method __del__() is called the finalizer method or, wrongly, the destructor method — the latter being wrong because it doesn’t actually destroy the object. Python calls __del__() upon deletion of a given instance. For example, the expression del my_obj will eventually initiate my_obj.__del__(). We call this a “Dunder Method” for “Double Underscore Method” … Read more
Python’s magic method __delete__() is called to delete an instance’s attribute. For example, the expression del my_obj.attr would result in attr.__delete__(my_obj), so you’d give the attribute itself the responsibility for its deletion on my_obj. We call this a “Dunder Method” for “Double Underscore Method” (also called “magic method”). To get a list of all dunder … Read more
Python’s magic method __getattr__() implements the built-in getattr() function that returns the value associated with a given attribute name. Additionally, __getattr__() is called if the normal attribute access (e.g., my_object.my_attribute) results in an AttributeError. We call this a “Dunder Method” for “Double Underscore Method” (also called “magic method”). To get a list of all dunder … Read more
Python’s magic method __setattr__() implements the built-in setattr() function that takes an object and an attribute name as arguments and removes the attribute from the object. We call this a “Dunder Method” for “Double Underscore Method” (also called “magic method”). To get a list of all dunder methods with explanation, check out our dunder cheat … Read more
Python has multiple special attributes that are defined per default for each class such as __name__, __module__, __dict__, __bases__, __doc__, and __annotations__. Each of these special attributes has a special meaning as shown in the following table: Attribute Type Description __name__ str The name of the class __module__ str The string name of the module … Read more
Python’s __new__(cls) magic method creates a new instance of class cls. The remaining arguments are passed to the object constructor. The return value is the newly-created object—an instance of cls. Basic Example The following example shows how each time you create an object of our custom class My_Class, Python calls the __new__() magic method. Output: … Read more
Syntax object.__missing__(self, key) The __missing__(self, key) method defines the behavior of a dictionary subclass if you access a non-existent key. More specifically, Python’s __getitem__() dictionary method internally calls the __missing__() method if the key doesn’t exist. The return value of __missing__() is the value to be returned when trying to access a non-existent key. We … Read more
🛑 Overriding this function is strongly discouraged. To change the semantics of the import statement, use import hooks instead! Still here? 😉 So, let’s get started learning the syntax of this function. You can also check out our in-depth article on the __import__ statement here. Syntax __import__(name, globals=None, locals=None, fromlist=(), level=0) Parameter Description name Import … Read more
Syntax class.__instancecheck__(self, instance) Python’s class.__instancecheck__(self, instance) method implements the isinstance(instance, class) built-in function. It should return True if instance is a direct or indirect instantiated object of class (e.g., via Python inheritance). We call this a “Dunder Method” for “Double Underscore Method” (also called “magic method”). To get a list of all dunder methods with … Read more
Syntax class.__subclasscheck__(self, subclass) Python’s class.__subclasscheck__(self, subclass) method implements the issubclass(subclass, class) built-in function. It should return True if subclass is a direct or indirect subclass of class using Python inheritance to define the subclass relationship. We call this a “Dunder Method” for “Double Underscore Method” (also called “magic method”). To get a list of all … Read more
Syntax object.__sizeof__(self, other) The Python __sizeof__() method returns the size of the object in bytes. The sys.getsizeof() method internally call’s __sizeof__() and adds some additional byte overhead, e.g., for garbage collection. Basic Example The following code snippet creates a list object x with three integers and measures its size in bytes (104) using the x.__sizeof__() … Read more