Chris🛑 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
In this article, you’ll learn about a basic algorithm, every computer scientist must know: the binary search algorithm. I have drawn the code from my NoStarch programming introductory book Python One-Liners: Applications Binary Search The algorithm has important practical applications in many basic data structures such as sets, trees, dictionaries, bags, bag trees, bag dictionaries, … 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
Python’s __reversed__ magic method implements the reversed() built-in function that returns a reverse iterator over the values of the given sequence such as a list, a tuple, or a string. Syntax __reversed__(self) Let’s have a look at an example next. Example In the following code, you create a Person class with one name attribute. The … Read more
Syntax and Definition The Python __contains__() magic method implements the membership operation, i.e., the in keyword. Semantically, the method returns True if the argument object exists in the sequence on which it is called, and False otherwise. For example, 3 in [1, 2, 3] returns True as defined by the list method [1, 2, 3].__contains__(3). … Read more
In which order does the nested ternary operator evaluate its conditions? Short Answer: The nested ternary operator ‘1’ if x else ‘2’ if y else ‘3’ evaluates the condition from left to right, i.e., ‘1’ if x else (‘2’ if y else ‘3’). In short, first condition first! Problem Formulation Given a nested ternary operator … Read more
Syntax object.__call__(self[, args…]) The Python __call__ method makes a class callable, so you can call objects of the class like a normal function. For example, if you define __call__(self) on an object x of class X, you can call it like so: x(). The return value of the called object is the return value of … Read more
Syntax object.__repr__(self) The Python __repr__ method returns a string representation of the object on which it is called. It implements the built-in repr() function. If you call print(x) an object x, Python internally calls x.__str__() to determine the string representation of object x. If this isn’t implemented, Python calls x.__repr__(). We call this a “Dunder … Read more
Question Recap the following regular expression concepts (more details in the article below): The dot character . in regular expressions matches any character excluding the newline character. For example, the pattern ‘c.t’ will match the strings ‘cat’, ‘cut’, or ‘czt’. The character class [ ] is a set of characters: if you use it in … Read more
Python’s __dir__() magic method implements the functionality of the dir() built-in function. Semantically, dir() returns all (function, object, or variable) names in a given scope. However, the magic method __dir__() converts any return value to a sorted list. Minimal Example The following code defines a custom class My_Class and overrides the __dir__() magic method to … Read more