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- Dependency management
- Declaring dependencies
- System Requirements
- Installation - *nix
- Installation - Windows
- Using Composer
- Autoloading
Introduction#
Composer is a tool for dependency management in PHP. It allows you to declare the dependent libraries your project needs and it will install them in your project for you.
Dependency management#
Composer is not a package manager. Yes, it deals with "packages" or libraries, but it manages them on a per-project basis, installing them in a directory (e.g. vendor
) inside your project. By default it will never install anything globally. Thus, it is a dependency manager.
This idea is not new and Composer is strongly inspired by node's npm and ruby's bundler. But there has not been such a tool for PHP.
The problem that Composer solves is this:
a) You have a project that depends on a number of libraries.
b) Some of those libraries depend on other libraries.
c) You declare the things you depend on.
d) Composer finds out which versions of which packages need to be installed, and installs them (meaning it downloads them into your project).
Declaring dependencies#
Let's say you are creating a project, and you need a library that does logging. You decide to usemonolog. In order to add it to your project, all you need to do is create a composer.json
file which describes the project's dependencies.
{
"require": {
"monolog/monolog": "1.2.*"
}
}
We are simply stating that our project requires some monolog/monolog
package, any version beginning with 1.2
.
System Requirements#
Composer requires PHP 5.3.2+ to run. A few sensitive php settings and compile flags are also required, but the installer will warn you about any incompatibilities.
To install packages from sources instead of simple zip archives, you will need git, svn or hg depending on how the package is version-controlled.
Composer is multi-platform and we strive to make it run equally well on Windows, Linux and OSX.
Installation - *nix#
Downloading the Composer Executable#
Locally#
To actually get Composer, we need to do two things. The first one is installing Composer (again, this means downloading it into your project):
curl -sS https://getcomposer.org/installer | php
Note: If the above fails for some reason, you can download the installer with
php
instead:
php -r "readfile('https://getcomposer.org/installer');" | php
This will just check a few PHP settings and then download composer.phar
to your working directory. This file is the Composer binary. It is a PHAR (PHP archive), which is an archive format for PHP which can be run on the command line, amongst other things.
You can install Composer to a specific directory by using the --install-dir
option and providing a target directory (it can be an absolute or relative path):
curl -sS https://getcomposer.org/installer | php -- --install-dir=bin
Globally#
You can place this file anywhere you wish. If you put it in your PATH
, you can access it globally. On unixy systems you can even make it executable and invoke it without php
.
You can run these commands to easily access composer
from anywhere on your system:
curl -sS https://getcomposer.org/installer | php
mv composer.phar /usr/local/bin/composer
Note: If the above fails due to permissions, run the
mv
line again with sudo.
Then, just run composer
in order to run Composer instead of php composer.phar
.
Globally (on OSX via homebrew)#
Composer is part of the homebrew-php project.
brew update
brew tap homebrew/dupes
brew tap homebrew/php
brew install composer
Installation - Windows#
Using the Installer#
This is the easiest way to get Composer set up on your machine.
Download and run Composer-Setup.exe, it will install the latest Composer version and set up your PATH so that you can just call composer
from any directory in your command line.
Manual Installation#
Change to a directory on your PATH
and run the install snippet to download composer.phar:
C:Usersusername>cd C:in
C:in>php -r "readfile('https://getcomposer.org/installer');" | php
Note: If the above fails due to readfile, use the
http
url or enable php_openssl.dll in php.ini
Create a new composer.bat
file alongside composer.phar
:
C:in>echo @php "%~dp0composer.phar" %*>composer.bat
Close your current terminal. Test usage with a new terminal:
C:Usersusername>composer -V
Composer version 27d8904
Using Composer#
We will now use Composer to install the dependencies of the project. If you don't have a composer.json
file in the current directory please skip to the Basic Usage chapter.
To resolve and download dependencies, run the install
command:
php composer.phar install
If you did a global install and do not have the phar in that directory run this instead:
composer install
Following the example above, this will download monolog into the vendor/monolog/monolog
directory.
Autoloading#
Besides downloading the library, Composer also prepares an autoload file that's capable of autoloading all of the classes in any of the libraries that it downloads. To use it, just add the following line to your code's bootstrap process:
require 'vendor/autoload.php';
Woah! Now start using monolog! To keep learning more about Composer, keep reading the "Basic Usage" chapter.
Found a typo? Something is wrong in this documentation? Just fork and edit it!
Composer and all content on this site are released under the MIT license.
转自:
https://getcomposer.org/doc/00-intro.md#installation-windows