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109 lines
2.9 KiB
Markdown
109 lines
2.9 KiB
Markdown
# Composer & Autoloading
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## Autoloading
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The function [spl_autoload_register()](https://www.php.net/manual/en/function.spl-autoload-register.php) allows to register a function that will be invoked when PHP needs to load a class/interface defined by the user.
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In `autoload.php`:
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```php
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# custom function
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function autoloader($class) {
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# __DIR__ -> path of calling file
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# $class -> className (hopefully same as file)
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# if class is in namespace $class -> Namespace\className (hopefully folders mirror Namespace)
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$class = str_replace("\\", DIRECTORY_SEPARATOR, $class); # avoid linux path separator issues
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$fileName = sprintf("%s\\path\\%s.php", __DIR__, $class);
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# or
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$filename = sprintf("%s\\%s.php", __DIR__, $class); # if class is in namespace
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if (file_exists($fileName)) {
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include $fileName;
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}
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}
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spl_autoload_register('autoloader'); // register function
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```
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In `file.php`:
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```php
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require "autoload.php";
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# other code
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```
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> **Note**: will fuck up if namespaces exists.
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### Multiple Autoloading
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It's possible to resister multiple autoloading functions by calling `spl_autoload_register()` multiple times.
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```php
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# prepend adds the function at the start of the queue
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# throws selects if errors in loading throw exceptions
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spl_autoload_register(callable $func, $throw=TRUE, $prepend=FALSE);
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spl_autoload_functions() # return a list of registered functions.
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```
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## [Composer](https://getcomposer.org/)
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Open Source project for dependency management and autoloading of PHP libraries and classes.
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Composer uses `composer.json` to define dependencies with third-party libraries.
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Libraries are downloaded through [Packagist](https://packagist.org/) and [GitHub](https://github.com/).
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In `composer.json`:
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```json
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{
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"require": {
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"php": ">=7.0",
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"monolog/monolog": "1.0.*"
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}
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}
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```
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### Installing Dependencies
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In the same folder of `composer.json` execute `composer install`.
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Composer will create:
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- `vendor`: folder containing all requested libraries
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- `vendor\autoload.php`: file for class autoloading
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- `composer.lock`
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In alternative `composer require <lib>` will add the library to the project and create a `composer.json` if missing.
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> **Note**: to ignore the php version use `composer <command> --ignore-platform-reqs`
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### Updating Dependencies
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To update dependencies use `composer update`. To update only the autoloading section use `composer dump-autoload`.
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### [Autoloading Project Classes](https://getcomposer.org/doc/04-schema.md#autoload)
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[PSR-4 Spec](https://www.php-fig.org/psr/psr-4/)
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Composer can also autoload classes belonging to the current project. It's sufficient to add the `autoload` keyword in the JSON and specify the path and autoload mode.
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```json
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{
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"autoload": {
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"psr-4": {
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"RootNamespace": "src/",
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"Namespace\\": "src/Namespace/",
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},
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"file": [
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"path/to/file.php",
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...
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]
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}
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}
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```
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