Merge pull request #452 from weaverryan/beginning-doc-changes
Proofreading the first and second chapters of the very well-written docspull/424/merge
commit
ac36d0c396
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@ -1,23 +1,30 @@
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# Introduction
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# Introduction
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Composer is a tool for dependency management in PHP. It allows you to declare
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Composer is a tool for dependency management in PHP. It allows you to declare
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the dependencies of your project and will install them for you.
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the dependent libraries your project needs and it will install them in your
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project for you.
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## Dependency management
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## Dependency management
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One important distinction to make is that composer is not a package manager. It
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Composer is not a package manager. Yes, it deals with "packages" or libraries, but
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deals with packages, but it manages them on a per-project basis. By default it
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it manages them on a per-project basis, installing them in a directory (e.g. `vendor`)
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will never install anything globally. Thus, it is a dependency manager.
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inside your project. By default it will never install anything globally. Thus,
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it is a dependency manager.
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This idea is not new by any means. Composer is strongly inspired by
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This idea is not new and Composer is strongly inspired by node's [npm](http://npmjs.org/)
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node's [npm](http://npmjs.org/) and ruby's [bundler](http://gembundler.com/).
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and ruby's [bundler](http://gembundler.com/). But there has not been such a tool
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But there has not been such a tool for PHP so far.
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for PHP.
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The problem that composer solves is the following. You have a project that
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The problem that Composer solves is this:
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depends on a number of libraries. Some of those libraries have dependencies of
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their own. You declare the things you depend on. Composer will then go ahead
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a) You have a project that depends on a number of libraries.
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and find out which versions of which packages need to be installed, and
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install them.
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b) Some of those libraries depend on other libraries .
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c) You declare the things you depend on
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d) Composer finds out which versions of which packages need to be installed, and
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installs them (meaning it downloads them into your project).
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## Declaring dependencies
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## Declaring dependencies
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@ -32,37 +39,50 @@ which describes the project's dependencies.
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}
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}
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}
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}
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We are simply stating that our project requires the `monolog/monolog` package,
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We are simply stating that our project requires some `monolog/monolog` package,
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any version beginning with `1.0`.
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any version beginning with `1.0`.
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## Installation
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## Installation
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To actually get it, we need to do two things. The first one is installing
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### 1) Downloading the Composer Executable
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composer:
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To actually get Composer, we need to do two things. The first one is installing
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Composer (again, this mean downloading it into your project):
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$ curl -s http://getcomposer.org/installer | php
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$ curl -s http://getcomposer.org/installer | php
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This will just check a few PHP settings and then download `composer.phar` to
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This will just check a few PHP settings and then download `composer.phar` to
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your working directory. This file is the composer binary.
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your working directory. This file is the Composer binary. It is a PHAR (PHP
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archive), which is an archive format for PHP which can be run on the command
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line, amongst other things.
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You can install composer to a specific directory by using the `--install-dir`
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You can install Composer to a specific directory by using the `--install-dir`
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option and providing a target directory (it can be an absolute or relative path):
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option and providing a target directory (it can be an absolute or relative path):
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$ curl -s http://getcomposer.org/installer | php -- --install-dir=bin
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$ curl -s http://getcomposer.org/installer | php -- --install-dir=bin
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After that we run the command for installing all dependencies:
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You can place this file anywhere you wish. If you put it in your `PATH`,
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you can access it globally. On unixy systems you can even make it
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executable and invoke it without `php`.
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### 2) Using Composer
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Next, run the command the `install` command to resolve and download dependencies:
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$ php composer.phar install
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$ php composer.phar install
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This will download monolog and dump it into `vendor/monolog/monolog`.
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This will download monolog into the `vendor/monolog/monolog` directory.
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## Autoloading
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## Autoloading
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After this you can just add the following line to your bootstrap code to get
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Besides downloading the library, Composer also prepares an autoload file that's
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autoloading:
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capable of autoloading all of the classes in any of the libraries that it
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downloads. To use it, just add the following line to your code's bootstrap
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process:
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require 'vendor/.composer/autoload.php';
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require 'vendor/.composer/autoload.php';
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That's all it takes to have a basic setup.
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Woh! Now start using monolog! To keep learning more about Composer, keep
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reading the "Basic Usage" chapter.
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[Basic Usage](01-basic-usage.md) →
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[Basic Usage](01-basic-usage.md) →
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@ -2,49 +2,36 @@
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## Installation
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## Installation
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To install composer, simply run this command on the command line:
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To install Composer, you just need to download the `composer.phar` executable.
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$ curl -s http://getcomposer.org/installer | php
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$ curl -s http://getcomposer.org/installer | php
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This will perform some checks on your environment to make sure you can
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For the details, see the [Introduction](00-intro.md) chapter.
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actually run it.
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Then it will download `composer.phar` and place it in your working directory.
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To check if Composer is working, just run the PHAR through `php`:
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`composer.phar` is the composer binary. It is a PHAR (PHP archive), which is
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an archive format for PHP which can be run on the command line, amongst other
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things.
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You can place this file anywhere you wish. If you put it in your `PATH`,
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you can access it globally. On unixy systems you can even make it
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executable and invoke it without `php`.
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You can install composer to a specific directory by using the `--install-dir`
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option and providing a target directory (it can be an absolute or relative path):
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$ curl -s http://getcomposer.org/installer | php -- --install-dir=bin
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To check if composer is working, just run the PHAR through `php`:
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$ php composer.phar
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$ php composer.phar
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This should give you a list of available commands.
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This should give you a list of available commands.
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> **Note:** You can also perform the checks only without downloading composer
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> **Note:** You can also perform the checks only without downloading Composer
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> by using the `--check` option. For more information, just use `--help`.
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> by using the `--check` option. For more information, just use `--help`.
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>
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>
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> $ curl -s http://getcomposer.org/installer | php -- --help
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> $ curl -s http://getcomposer.org/installer | php -- --help
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## Project setup
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## `composer.json`: Project Setup
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To start using composer in your project, all you need is a `composer.json`
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To start using Composer in your project, all you need is a `composer.json`
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file. This file describes the dependencies of your project and may contain
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file. This file describes the dependencies of your project and may contain
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other metadata as well.
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other metadata as well.
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The [JSON format](http://json.org/) is quite easy to write. It allows you to
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The [JSON format](http://json.org/) is quite easy to write. It allows you to
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define nested structures.
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define nested structures.
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### The `require` Key
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The first (and often only) thing you specify in `composer.json` is the
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The first (and often only) thing you specify in `composer.json` is the
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`require` key. You're simply telling composer which packages your project
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`require` key. You're simply telling Composer which packages your project
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depends on.
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depends on.
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{
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{
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@ -53,12 +40,13 @@ depends on.
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}
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}
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}
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}
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As you can see, `require` takes an object that maps package names to versions.
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As you can see, `require` takes an object that maps **package names** (e.g. `monolog/monolog`)
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to **package versions** (e.g. `1.0.*`).
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## Package names
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### Package Names
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The package name consists of a vendor name and the project's name. Often these
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The package name consists of a vendor name and the project's name. Often these
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will be identical. The vendor name exists to prevent naming clashes. It allows
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will be identical - the vendor name just exists to prevent naming clashes. It allows
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two different people to create a library named `json`, which would then just be
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two different people to create a library named `json`, which would then just be
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named `igorw/json` and `seldaek/json`.
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named `igorw/json` and `seldaek/json`.
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@ -68,10 +56,10 @@ allows adding more related projects under the same namespace later on. If you
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are maintaining a library, this would make it really easy to split it up into
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are maintaining a library, this would make it really easy to split it up into
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smaller decoupled parts.
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smaller decoupled parts.
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## Package versions
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### Package Versions
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We are also requiring the version `1.0.*` of monolog. This means any version
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We are requiring version `1.0.*` of monolog. This means any version in the `1.0`
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in the `1.0` development branch. It would match `1.0.0`, `1.0.2` and `1.0.20`.
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development branch. It would match `1.0.0`, `1.0.2` or `1.0.20`.
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Version constraints can be specified in a few different ways.
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Version constraints can be specified in a few different ways.
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@ -80,14 +68,14 @@ Version constraints can be specified in a few different ways.
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* **Range:** By using comparison operators you can specify ranges of valid
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* **Range:** By using comparison operators you can specify ranges of valid
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versions. Valid operators are `>`, `>=`, `<`, `<=`. An example range would be
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versions. Valid operators are `>`, `>=`, `<`, `<=`. An example range would be
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`>=1.0`. You can define multiple of these, separated by comma: `>=1.0,<2.0`.
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`>=1.0`. You can define multiple ranges, separated by a comma: `>=1.0,<2.0`.
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* **Wildcard:** You can specify a pattern with a `*` wildcard. `1.0.*` is the
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* **Wildcard:** You can specify a pattern with a `*` wildcard. `1.0.*` is the
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equivalent of `>=1.0,<1.1-dev`.
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equivalent of `>=1.0,<1.1-dev`.
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## Installing dependencies
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## Installing Dependencies
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To fetch the defined dependencies into the local project, you simply run the
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To fetch the defined dependencies into your local project, just run the
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`install` command of `composer.phar`.
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`install` command of `composer.phar`.
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$ php composer.phar install
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$ php composer.phar install
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@ -104,29 +92,33 @@ In case of monolog it will put it into `vendor/monolog/monolog`.
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Another thing that the `install` command does is it adds a `composer.lock`
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Another thing that the `install` command does is it adds a `composer.lock`
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file into your project root.
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file into your project root.
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## Lock file
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## `composer.lock` - The Lock File
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After installing the dependencies, composer writes the list of the exact
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After installing the dependencies, Composer writes the list of the exact
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versions it installed into a `composer.lock` file. This locks the project
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versions it installed into a `composer.lock` file. This locks the project
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to those specific versions.
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to those specific versions.
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**Commit your project's `composer.lock` into version control.**
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**Commit your project's `composer.lock` (along with `composer.json`) into version control.**
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The reason is that anyone who sets up the project should get the same version.
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This is important because the `install` command checks if a lock file is present,
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The `install` command will check if a lock file is present. If it is, it will
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and if it is, it downloads the versions specified there (regardless of what `composer.json`
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use the versions specified there. If not, it will resolve the dependencies and
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says). This means that anyone who sets up the project will download the exact
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create a lock file.
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same version of the dependencies.
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If any of the dependencies gets a new version, you can update to that version
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If no `composer.json` lock file exists, it will read the dependencies and
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by using the `update` command. This will fetch the latest matching versions and
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versions from `composer.json` and create the lock file.
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also update the lock file.
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This means that if any of the dependencies get a new version, you won't get the updates.
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automatically. To update to the new version, use `update` command. This will fetch
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the latest matching versions (according to your `composer.json` file) and also update
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the lock file with the new version.
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$ php composer.phar update
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$ php composer.phar update
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## Packagist
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## Packagist
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[Packagist](http://packagist.org/) is the main composer repository. A composer
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[Packagist](http://packagist.org/) is the main Composer repository. A Composer
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repository is basically a package source. A place where you can get packages
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repository is basically a package source: a place where you can get packages
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from. Packagist aims to be the central repository that everybody uses. This
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from. Packagist aims to be the central repository that everybody uses. This
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means that you can automatically `require` any package that is available
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means that you can automatically `require` any package that is available
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there.
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there.
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@ -134,20 +126,20 @@ there.
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If you go to the [packagist website](http://packagist.org/) (packagist.org),
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If you go to the [packagist website](http://packagist.org/) (packagist.org),
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you can browse and search for packages.
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you can browse and search for packages.
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Any open source project using composer should publish their packages on
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Any open source project using Composer should publish their packages on
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packagist.
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packagist. A library doesn't need to be on packagist to be used by Composer,
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but it makes life quite a bit simpler.
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## Autoloading
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## Autoloading
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For libraries that follow the [PSR-0](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md)
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For libraries that follow the [PSR-0](https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-0.md)
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naming standard, composer generates a
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naming standard, Composer generates a `vendor/.composer/autoload.php` file
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`vendor/.composer/autoload.php` file for autoloading. You can simply include
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for autoloading. You can simply include this file and you will get autoloading
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this file and you will get autoloading for free.
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for free.
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require 'vendor/.composer/autoload.php';
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require 'vendor/.composer/autoload.php';
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This makes it really easy to use third party code, because you only
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This makes it really easy to use third party code: For monolog, it
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have to add one line to `composer.json` and run `install`. For monolog, it
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means that we can just start using classes from it, and they will be
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means that we can just start using classes from it, and they will be
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autoloaded.
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autoloaded.
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Reference in New Issue