Design Patterns: Creational Patterns

Design Patterns

• Design patterns categorize into 3 sub-classifications: Creational, Structural, and Behavioral patterns
• Creational patterns focus on object creation based on specific criteria and controlled instantiation.
• Structural patterns are about organizing classes and objects into larger structures, offering new functionality.
• Behavioral patterns identify and implement common communication patterns between objects.
• Design patterns improve code readability for programmers familiar with them
• Design patterns help prevent subtle issues leading to major software issues.

Creational Patterns

• Abstract Factory - provides an interface for creating families of related objects. Ensures consistency within a family.
• Builder - separates the construction of a complex object from its representation
• Factory Method defines an interface for creating objects. Allows subclasses to decide which class to instantiate.
• Prototype: specifies the kinds of objects to create using a prototypical instance. Creates new objects by copying this prototype.
• Singleton: ensures that a class has only one instance and provides a global point of access.

Structural Patterns

• Adapter: converts the interface of a class into another interface clients expect. Enables incompatible classes to work together.
• Bridge: Decouples an abstraction from its implementation. Allows both to vary independently
• Composite: composes objects into tree structures to represent part-whole hierarchies. Lets clients treat individual objects and compositions uniformly.
• Decorator: dynamically adds responsibilities to an object. Provides a flexible alternative to subclassing for extending functionality.
• Facade: provides a simplified interface to a complex subsystem
• Flyweight: shares objects to support large numbers of fine-grained objects efficiently. Uses sharing to support large numbers of fine-grained objects efficiently
• Proxy: provides a surrogate or placeholder for another object to control access to it.

PHP - The '$this' Keyword

• Refers to the current object
• Only available inside methods
• Allows access and manipulation of object properties and methods within the object's context

PHP - Inheritance

• A child class inherits properties and methods from a parent class using the extends keyword.
• Inherited classes can have their own properties and methods in addition to those inherited.
• Inheritance allows code reuse and creates a hierarchy of classes.

PHP - User-Defined Functions

• Functions are reusable blocks of code that perform specific tasks
• Defined using the function keyword followed by the function name and parentheses.
• Code within the function is executed only when the function is called.
• Can accept arguments (inputs) and return values (outputs)

Scripting Techniques for Test Automation

• Linear scripting: simple record and playback of user actions. Can be redundant and inflexible.
• Structured scripting: incorporates control structures like if-else, for and while loops for decision-making and iteration.
• Shared scripting: Develops reusable scripts for common functionality across different tests. Enhances modularity and code reuse.
• Data-driven scripting: Separates test data from the script, stored in external data files. Provides flexibility to adjust test data without modifying the script.
• Keyword-driven testing: Uses keywords to represent test actions and stores them in external data files. Requires a library for interpretation.

Client-Side Scripting

• Client-side scripting executes code in the user's browser (client) without needing server interaction.
• This speeds up website performance and reduces server load.
• Examples include JavaScript, HTML, and CSS.
• JavaScript is widely used for dynamic web page elements, user interaction, and validation.

Javascript

• Initially called LiveScript.
• Released with Netscape 2.0 in 1995.
• Server-side JavaScript frameworks are also available.

MySQLi

• MySQLi is a PHP extension for interacting with MySQL databases.

Opening a Connection to MySQL

• The mysqli_connect() function establishes a connection to a MySQL server.

Creating a MySQL Database

• The CREATE DATABASE statement creates a new database.

Creating a MySQL Table

• The CREATE TABLE statement creates a new table within a database.
• It defines columns, their data types, and optional attributes like NOT NULL, DEFAULT, AUTO_INCREMENT, and PRIMARY KEY.

Inserting Data Into MySQL

• The INSERT INTO statement adds new records to a table.
• String values are enclosed in single quotes.
• Numeric values are not quoted.
• The word NULL is not quoted.

Selecting Data From MySQL

• The SELECT statement retrieves data from a table.

Filtering Data with WHERE Clause

• The WHERE clause filters selected data based on specified conditions.

Ordering Data with ORDER BY Clause

• The ORDER BY clause sorts the retrieved data in ascending or descending order.
• The default order is ascending.