All posts by Pramod T P

Friend Function

A friend function is a function that is not a member of a class but has access to the class’s private and protected members. Friend functions are not considered class members; they are normal external functions that are given special access privileges.

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Accessors

Accessors are instructions that generally give a property of method permission to be accessible in different ways. There are three types:

public: This property or permission is accessible from anywhere in the application.

protected: This property or permission is accessible only from a class that extends the parent class.

private: This property or permission is accessible only within the current class you are working with.

The really neat thing about access is that it protects your code should other developers be working on the same project. If you don’t want them to be able to touch something, don’t give him access to it.

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Object Oriented Concepts

Class: This is a programmer-defined datatype, which includes local functions as well as local data. You can think of a class as a template for making many instances of the same kind (or class) of object.

Object: An individual instance of the data structure defined by a class. You define a class once and then make many objects that belong to it. Objects are also known as instance.

Member Variable: These are the variables defined inside a class. This data will be invisible to the outside of the class and can be accessed via member functions. These variables are called attribute of the object once an object is created.

Member function: These are the function defined inside a class and are used to access object data.

Inheritance: When a class is defined by inheriting existing function of a parent class then it is called inheritance. Here child class will inherit all or few member functions and variables of a parent class.

Parent class: A class that is inherited from by another class. This is also called a base class or super class.

Child Class: A class that inherits from another class. This is also called a subclass or derived class.

Polymorphism: This is an object oriented concept where same function can be used for different purposes. For example function name will remain same but it make take different number of arguments and can do different task.

Overloading: a type of polymorphism in which some or all of operators have different implementations depending on the types of their arguments. Similarly functions can also be overloaded with different implementation.

Data Abstraction: Any representation of data in which the implementation details are hidden (abstracted).

Encapsulation: refers to a concept where we encapsulate all the data and member functions together to form an object.

Constructor: refers to a special type of function which will be called automatically whenever there is an object formation from a class.

Destructors: refers to a special type of function which will be called automatically whenever an object is deleted or goes out of scope.

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nginx

nginx [engine x] is an HTTP and reverse proxy server, a mail proxy server, and a generic TCP proxy server, originally written by Igor Sysoev. For a long time, it has been running on many heavily loaded Russian sites including Yandex, Mail.Ru, VK, and Rambler. According to Netcraft, nginx served or proxied 21.64% busiest sites in May 2015.

Nginx (pronounced engine-x) is a free, open-source, high-performance HTTP server and reverse proxy, as well as an IMAP/POP3 proxy server. Igor Sysoev started development of Nginx in 2002, with the first public release in 2004. Nginx now hosts nearly 12.18% (22.2M) of active sites across all domains. Nginx is known for its high performance, stability, rich feature set, simple configuration, and low resource consumption.

Nginx is one of a handful of servers written to address the C10K problem. Unlike traditional servers, Nginx doesn’t rely on threads to handle requests. Instead it uses a much more scalable event-driven (asynchronous) architecture. This architecture uses small, but more importantly, predictable amounts of memory under load.
Even if you don’t expect to handle thousands of simultaneous requests, you can still benefit from Nginx’s high-performance and small memory footprint. Nginx scales in all directions: from the smallest VPS all the way up to clusters of servers.

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Encapsulation

Encapsulation is the packing of data and functions into a single component. The features of encapsulation are supported using classes in most object-oriented programming languages, although other alternatives also exist.

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Abstract Classes

PHP 5 introduces abstract classes and methods. Classes defined as abstract may not be instantiated, and any class that contains at least one abstract method must also be abstract. Methods defined as abstract simply declare the method’s signature – they cannot define the implementation.

When inheriting from an abstract class, all methods marked abstract in the parent’s class declaration must be defined by the child; additionally, these methods must be defined with the same (or a less restricted) visibility. For example, if the abstract method is defined as protected, the function implementation must be defined as either protected or public, but not private. Furthermore the signatures of the methods must match, i.e. the type hints and the number of required arguments must be the same. For example, if the child class defines an optional argument, where the abstract method’s signature does not, there is no conflict in the signature.

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