Found 10784 Articles for Python

My Python class defines __del__ but it is not called when I delete the object

AmitDiwan
Updated on 19-Sep-2022 13:46:46

2K+ Views

The __del__ is magic method in Python. The magic methods that allow us to do some pretty neat tricks in object-oriented programming. They are also called Dunder methods. These methods are identified by two underscores (__) used as prefix and suffix. In Python, we create an oject using the __new__() and initialize using __init__(). However, to destruct an object, we have __del__(). Example Let us create and delete an object − class Demo: def __init__(self): print("We are creating an object."); # destructor def __del__(self): ... Read More

How can a Python subclass control what data is stored in an immutable instance?

AmitDiwan
Updated on 19-Sep-2022 13:45:56

211 Views

For this, at first understand what is __new__() method in Python. When subclassing an immutable type, override the __new__() method instead of the __init__() method. The __new__ method gets called when an object is created whereas the __init__ method will be called to initialize the object. These are magic methods. The magic methods that allow us to do some pretty neat tricks in object-oriented programming. They are also called Dunder methods. These methods are identified by two underscores (__) used as prefix and suffix. Display the magic methods inherited by int class Example Using the fir(), we can print the ... Read More

How do I cache method calls in Python?

AmitDiwan
Updated on 19-Sep-2022 13:40:15

2K+ Views

The two tools for caching methods are functools.cached_property() and functools.lru_cache(). Both the module is part of the functools module. The functools module is for higher-order functions: functions that act on or return other functions. Let us first install and import the functools module − Install functools To install the functools module, use the pip − pip install functools Import functools To import functools − import functools Let us understand both the caching one by one − cached_property() useful for expensive computed properties of instances that are otherwise effectively immutable. The cached_property approach only works with methods that do ... Read More

Why does the result of id() appear to be not unique in Python?

AmitDiwan
Updated on 19-Sep-2022 13:39:36

147 Views

The id() method in Python return the identity of an object i.e. a unique id for the specified object. Now, you would be wondering, what is this id(). The id here is the object's memory address, an integer guaranteed to be unique and constant for this object during its lifetime. Two objects with non-overlapping lifetimes may have the same id() value. Syntax id(object) This object can be object, String, Number, List, etc. Unique id of List Object Example In this example, we will get the unique id of the list object using the id() − myList = ["john", "tom", ... Read More

When can I rely on identity tests with the is operator in Python?

AmitDiwan
Updated on 19-Sep-2022 13:38:33

58 Views

Example The is operator is an identity operator in Python. It tests for object identity. Let us see an example − x = ["Paul", "Mark"] y = ["Paul", "Mark"] z = x # Python IS operator print(x is z) Output True Let’s say we consider another example, wherein the test a is b is equivalent to − id(a) == id(b) The key property of an identity test is that an object is always identical to itself, a is a always returns True. Identity tests are usually faster than equality tests. And unlike equality tests, identity tests ... Read More

How do I create static class data and static class methods in Python?

AmitDiwan
Updated on 19-Sep-2022 13:35:57

2K+ Views

Python includes the concept of static class data and static class methods. The static class data Here, define a class attribute for the static class data. Explicitly use the class name in the assignment, if you want to assign a new value to the attribute − class Demo: count = 0 def __init__(self): Demo.count = Demo.count + 1 def getcount(self): return Demo.count We can also return the following instead return ... Read More

How can I organize my Python code to make it easier to change the base class?

AmitDiwan
Updated on 19-Sep-2022 13:35:18

272 Views

Before learning how to change the base class, let us first understand the concept of base and derived class in Python. We will learn about Base and Derived class using the concept of Inheritance. In multiple inheritance, the features of all the base classes are inherited into the derived class. Let us see the syntax − Syntax Class Base1: Body of the class Class Base2: Body of the class Class Base3: Body of the class . . . Class BaseN: Body of the class Class ... Read More

How do I get int literal attribute instead of SyntaxError in Python?

AmitDiwan
Updated on 19-Sep-2022 13:32:12

220 Views

To get int literal attribute instead of SyntaxError, use a space or parenthesis. The int literal is a part if Numeric Literals in Python. Numeric Literals also includes the following four different numerical types − int (signed integers) − They are often called just integers or ints, are positive or negative whole numbers with no decimal point. long (long integers ) − Also called longs, they are integers of unlimited size, written like integers and followed by an uppercase or lowercase L. float (floating point real values) − Also called floats, they represent real numbers and are written with ... Read More

Why does -22 // 10 return -3 in Python?

AmitDiwan
Updated on 19-Sep-2022 13:30:57

248 Views

In Python, -22//10 returns -3 because of the concept of Floor Division i.e. Double Slash Operator. The // is the Double Slash i.e. Arithmetic Operator. Let us first understand about it. Floor Division in Python The division of operands where the result is the quotient in which the digits after the decimal point are removed. But if one of the operands is negative, the result is floored, i.e., rounded away from zero (towards negative infinity). In Python, the // is the double slash operator i.e. Floor Divison. The // operator is used to perform division that rounds the result down ... Read More

How it is possible to write obfuscated oneliners in Python?

AmitDiwan
Updated on 19-Sep-2022 13:28:41

259 Views

Yes, it is possible to write obfuscated one-liners in Python using Lambda. Before moving further, let us first understand what are Lambdas in Python. Python Lambda The Lambda expressions allow defining anonymous functions. A lambda function is an anonymous function i.e. a function without a name. Let us see the syntax − lambda arguments: expressions The keyword lambda defines a lambda function. A lambda expression contains one or more arguments, but it can have only one expression. Example Let us see an example − myStr = "Thisisit!" (lambda myStr : print(myStr))(myStr) Output Thisisit! Merge Elements in a ... Read More

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