How can you understand the design principles and goals behind the latest PHP code specification by reading its source code?

How to understand the design principles and goals behind it by reading the source code of the latest PHP code specification?

Introduction:
When writing high-quality PHP code, it is very important to follow certain code specifications. Through code specifications, the readability, maintainability and scalability of the code can be improved. For the PHP language, there is a widely adopted code specification, namely PSR (PHP Standards Recommendations). This article will introduce how to understand the design principles and goals behind the latest PHP code specification by reading the source code, and deepen your understanding through code examples.

1. PSR Overview:
1.1 PSR Definition:
PSR (PHP Standards Recommendations) is a series of standard specifications for PHP development developed by PHP FIG (Framework Interoperability Group). Its purpose is to promote interoperability between PHP applications, libraries and frameworks.

1.2 PSR classification:
PSR can be divided into multiple sub-specifications according to specific specification content and goals, such as the following commonly used sub-specifications:

• PSR-1: Basic Coding style specifications require the use of strict namespaces, class and method naming conventions, and standardized file automatic loading mechanisms.
• PSR-2: Code style specification, which defines the code writing format for classes, methods, attributes, etc., including indentation, line breaks, brackets, etc. Four-space indentation is enforced, and each line must be no longer than 80 characters.
• PSR-3: Logging interface specification, which defines a simple logging interface for logging in applications.
• PSR-4: Autoloading specification, which maps namespaces to file paths in the file system, for automatic loading of classes and interfaces.
• PSR-12: Expands PSR-2 and more strictly standardizes the code writing format, including comments, naming conventions, arrangement of properties and methods, etc.

2. How to read the source code:
In order to deeply understand the design principles and goals of PSR, you can explore it by reading its source code. Here are several methods and steps for reading source code.

2.1 Download source code:
First, you need to download the source code of PSR from the official website (https://www.php-fig.org/psr/). You can choose to download a specified PSR. Specifications or download them all.

2.2 Read the source code:
Next, open the source code folder in the code editor you like to read. You can choose to start reading from the latest version of the source code. When reading the code, you can pay attention to the following points:

• Understand the specific content and purpose of each PSR specification. Each specification has a clear goal and design principle.
• Understand the purpose of the rules and conventions proposed by each specification by reviewing the comments and documentation in the specification.
• Pay attention to reading the code examples in the specification. These sample codes are the best practices for actual application of the specification and help to understand the correct use of the specification.

The following is a sample code that shows the provisions of the PSR-2 specification regarding code indentation and line breaks:

<?php
class MyClass
{
    public function myMethod()
    {
        if ($condition) {
            // do something
        } else {
            // do something else
        }
    }
}
?>

3. Code sample analysis:
Next, By parsing the sample code, you can understand the design principles and goals of code indentation and line wrapping in the PSR-2 specification.

3.1 Indentation specification:
According to the PSR-2 specification, code should be indented using four spaces. The purpose of this indentation style is to improve code readability and maintainability. Using a unified indentation style makes your code appear consistently across different editors and operating systems, and makes it easier to find and debug your code.

3.2 Line break specification:
PSR-2 specification also stipulates line breaks of code. The code recommends line wrapping if each line does not exceed 80 characters. The purpose of this restriction is to prevent overly long lines of code from being fully displayed on some editors or display devices, and to also make the code easier to read and understand.

4. Summary:
By reading the source code of the latest PHP code specification, you can better understand the design principles and goals behind it. When reading the source code, we can combine the comments, documentation, and code examples in the specification to deepen our understanding. By understanding the PSR specification, we can write PHP code that is more readable, maintainable, and scalable. I hope this article will help you understand the design principles and goals of PSR.

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