An in-depth study of the historical evolution of PHP coding standards

In-depth study of the historical evolution of PHP code specifications

Introduction:
In the software development process, code standardization is important for project maintainability and teamwork Very important. As a widely used scripting language, PHP's code specifications have also undergone many years of evolution and development. This article will delve into the historical evolution of PHP coding standards and demonstrate the changes through code examples.

1. Origin
The earliest PHP code specifications were not systematic. They only guided developers through some official documents and non-standard example codes in the community. The lack of uniformly defined specifications leads to diversified code styles and poor readability and consistency.

2. PEAR style
With the development of PHP, the PEAR (PHP Extension and Application Repository) project was established in 1999 with the purpose of providing a set of common standardized components and code specifications for PHP. The PEAR style code specification has become the mainstream in the PHP development community. Its characteristics include:

1. Use 4 spaces for indentation.
2. Use curly braces to occupy a line.
3. Use all lowercase and underscore naming style.

Sample Code 1:

function my_function() { if ($condition) { // some code } else { // some code } }

However, the PEAR style coding specification is not without controversy. One point of contention is the use of uppercase constant names instead of all lowercase and underscores. In addition, the PEAR style has too simple naming requirements for functions and methods and lacks certain expressive capabilities.

3. PSR Standard
PSR (PHP Standard Recommendation) is a series of PHP code specifications developed by the PHP Framework Alliance in 2012. The purpose is to provide a unified set of standards for PHP developers. These standards were widely participated and discussed by the developer community and became the cornerstone of modern PHP code specifications.

The PSR standard includes multiple branches, such as PSR-1 (Basic Coding Standard), PSR-2 (Coding Style), etc. The following uses PSR-1 and PSR-2 as examples to introduce their main features.

1. PSR-1 (Basic Coding Standard)
   PSR-1 standardizes the basic coding style of PHP, including the following requirements:
   1) PHP code must useor=tag.
2) The PHP file should only contain PHP code and no other content.
3) Class naming should follow the camel case naming convention.

      

       
PSR-2 (coding style)
PSR-2 standardizes the coding style of PHP code, including the following requirements :
1) Use 4 spaces for indentation.
2) Use curly brackets to occupy a line.
3) Use big camel case to name classes, interfaces and constants, and use small camel case to name variables and functions.
4) Each line of code must not exceed 80 characters.
      
      
Sample code 3:
      

      
Through the formulation of the PSR standard, PHP code specifications have been more widely recognized, which has also enabled different PHP frameworks and projects to better interoperate and cooperate. .
      
Conclusion:
The evolution of PHP code specifications marks the PHP community’s continuous pursuit of code quality and readability. From the earliest confusion, to the unification of PEAR style, and then to the formulation of PSR standards, the development of PHP code specifications has provided unified standards for PHP developers, making the code more readable and maintainable, and promoting cooperation among developers. .
      
However, code specifications are not static. With the development of technology and the needs of developers, new standards and specifications may emerge. Therefore, as developers, we should constantly pay attention to and learn the latest code specifications, and constantly improve our code quality and technical level.
      
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