Programming Articles - Page 594 of 3363

All parameters (arguments) in the Python language are passed by reference. It means if you change what a parameter refers to within a function, the change also reflects back in the calling function. Achieve this in the following ways − Return a Tuple of the Results Example In this example, we will return a tuple of the outcome − # Function Definition def demo(val1, val2): val1 = 'new value' val2 = val2 + 1 return val1, val2 x, y = 'old value', 5 # Function call print(demo(x, y)) ... Read More

Threads are sometimes called light-weight processes and they do not require much memory overhead; they are cheaper than processes. A thread has a beginning, an execution sequence, and a conclusion. There are two modules which support the usage of threads in Python3 − _thread − Deprecated in Python 3 Threading − Introduced in Python 2.4 The threading Module The newer threading module included with Python 2.4 provides much more powerful, high-level support for threads than the thread module. The threading module exposes all the methods of the thread module and provides some additional methods − threading.activeCount() ... Read More

Operator precedence determines the grouping of terms in an expression and decides how an expression is evaluated. The comma is not an operator in Python; therefore, the precedence concept doesn’t work here. Before moving further, let us first see the precedence of operators in Python from highest precedence to lowest. S.No. Operator & Desc 1 ** Exponentiation (raise to the power) 2 ~ + - Complement, unary plus and minus (method names for the last two are +@ and -@) 3 * / % // Multiply, divide, modulo and floor division ... Read More

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

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

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

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

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

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

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