Serverside Webscripting [JLW322]

06.code
organization

Include & Require

Include

• Include the contents of one PHP file into another PHP file with the include keyword
  • Contents 01_include.php

    <?php
    
    	$x++;

  • Contents 01.php

    <?php
    
    	$x = 0;
    
    	include '01_include.php';
    	include '01_include.php';
    
    	echo $x;

Include once

• Include the contents of one PHP file only once into another PHP file with the include_once keyword
  • Contents 01b.php

    <?php
    
    	$x = 0;
    
    	include_once '01_include.php';
    	include_once '01_include.php';
    
    	echo $x;

Include #fail

• If an included file does not exist, you'll get a notice
  • Contents 01c.php

    <?php
    
    	$x = 0;
    
    	include '01_nonexistent.php';
    	include '01_include.php';
    
    	echo $x;

require & require_once

• require does the same as include yet it won't give a notice but will result in a fatal error and stop the process
  • Contents 02.php

    <?php
    
    	$x = 0;
    
    	require '02_nonexistent.php';
    
    	echo $x;

• I bet you can guess what require_once does
• Best practice: always use require or require_once instead of include*

DRY

DRY?

• DRY = Don't Repeat Yourself
  • “Every piece of knowledge must have a single, unambiguous, authoritative representation within a system”
• If you have two files in your project which contain the same function/value you're not DRY, but WET (Write Everything Twice)
• One of the ways to remain DRY is to work with includes

What needs to be DRY?

1. Projectwide variables
2. Recurring functionality

Projectwide variables

• A variable that is constant and used throughout the project, yet is specific to the very project
  • The mailserver to use when sending an e-mail
  • The target mailaddress to send the various forms to
  • The database configuration data (server, username, password, databasename)
  • The API keys your website uses
  • ...
• → You might also call this the configuration data

How to?

• Create a config.php file and define all variables into it

  <?php
  
  define('MAIL_SERVER', 'localhost');
  define('MAIL_PORT', 25);
  
  define('DB_HOST', 'localhost');
  define('DB_USER', 'root');
  define('DB_PASS', 'Azerty123');
  define('DB_NAME', 'world');
  
  // EOF

  • Include this file everywhere, as the very first file to include and use the defined constants
• config.php is the only file that may be changed when publishing a site onto a server

Recurring Functionality

• Say you have a function isValidImageExtension() that checks whether a filename ends in .jpg/.jpeg/.gif
  • It'd be stupid to define this function in every file where you need it
  • What if you want to check for .png too? You'll edit all files?
• A class definition — which itself is a step towards becoming DRY — only needs to be defined once

How to?

• Create a functions.php and put all often used functions in it
  • Include this file everywhere, as the very first file to include and use the defined constants
• If you define a class, define it in a separate file on disk
  • Include the file when necessary

On Disk / Summary

Code Organization on disk

• Make use of an includes/ subfolder to store config.php and functions.php in
  • Define your configuration data in config.php
  • Place commonly used functions in functions.php
  • Always include these two files in your project
• Store all classes into includes/classes/
  • Include when necessary

Questions?

Sources