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reworking basic usage, added versions article

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9
doc/00-intro.md
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@ -77,15 +77,16 @@ The installer will just check a few PHP settings and then download
is a PHAR (PHP archive), which is an archive format for PHP which can be run on
the command line, amongst other things.
Now just run `php composer.phar` in order to run Composer.
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):
option and additionally (re)name it as well using the `--filename` option:
```sh
curl -sS https://getcomposer.org/installer | php -- --install-dir=bin
curl -sS https://getcomposer.org/installer | php -- --install-dir=bin --filename=composer
```
Now just run `php composer.phar` in order to run Composer.
Now just run `php bin/composer` in order to run Composer.
#### Globally

167
doc/01-basic-usage.md
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@ -1,8 +1,12 @@
# Basic usage
## Installing
## Introduction
If you have not yet installed Composer, refer to the [Intro](00-intro.md) chapter.
If you have not yet installed Composer, refer to the [Intro](00-intro.md)
chapter. For our basic usage introduction, we will be installing
`monolog/monolog`, a logging library. Note that for the sake of simplicity,
this introduction will assume you have performed a [local](00-intro.md#locally)
install of Composer.
## `composer.json`: Project Setup
@ -10,9 +14,6 @@ To start using Composer in your project, all you need is a `composer.json`
file. This file describes the dependencies of your project and may contain
other metadata as well.
The [JSON format](http://json.org/) is quite easy to write. It allows you to
define nested structures.
### The `require` Key
The first (and often only) thing you specify in `composer.json` is the
@ -27,15 +28,15 @@ depends on.
}
```
As you can see, `require` takes an object that maps **package names** (e.g. `monolog/monolog`)
to **package versions** (e.g. `1.0.*`).
As you can see, `require` takes an object that maps **package names**
(e.g. `monolog/monolog`) to **version constraints** (e.g. `1.0.*`).
### Package Names
The package name consists of a vendor name and the project's name. Often these
will be identical - the vendor name just exists to prevent naming clashes. It allows
two different people to create a library named `json`, which would then just be
named `igorw/json` and `seldaek/json`.
will be identical - the vendor name just exists to prevent naming clashes. It
allows two different people to create a library named `json`, which would then
just be named `igorw/json` and `seldaek/json`.
Here we are requiring `monolog/monolog`, so the vendor name is the same as the
project's name. For projects with a unique name this is recommended. It also
@ -45,53 +46,20 @@ smaller decoupled parts.
### Package Versions
In the previous example we were requiring version [`1.0.*`](http://semver.mwl.be/#?package=monolog%2Fmonolog&version=1.0.*) of monolog. This
means any version in the `1.0` development branch. It would match `1.0.0`,
`1.0.2` or `1.0.20`.
In the previous example we were requiring version
[`1.0.*`](http://semver.mwl.be/#?package=monolog%2Fmonolog&version=1.0.*) of
monolog. This means any version in the `1.0` development branch. It is the
equivalent of saying versions that match `>=1.0 <1.1`.
Version constraints can be specified in a few different ways.
Name | Example | Description
-------------- | ------------------------------------------------------------------------ | -----------
Exact version | `1.0.2` | You can specify the exact version of a package.
Range | `>=1.0` `>=1.0 <2.0` <code>&gt;=1.0 &lt;1.1 &#124;&#124; &gt;=1.2</code> | By using comparison operators you can specify ranges of valid versions. Valid operators are `>`, `>=`, `<`, `<=`, `!=`. <br />You can define multiple ranges. Ranges separated by a space (<code> </code>) or comma (`,`) will be treated as a **logical AND**. A double pipe (<code>&#124;&#124;</code>) will be treated as a **logical OR**. AND has higher precedence than OR.
Hyphen Range | `1.0 - 2.0` | Inclusive set of versions. Partial versions on the right include are completed with a wildcard. For example `1.0 - 2.0` is equivalent to `>=1.0.0 <2.1` as the `2.0` becomes `2.0.*`. On the other hand `1.0.0 - 2.1.0` is equivalent to `>=1.0.0 <=2.1.0`.
Wildcard | `1.0.*` | You can specify a pattern with a `*` wildcard. `1.0.*` is the equivalent of `>=1.0 <1.1`.
Tilde Operator | `~1.2` | Very useful for projects that follow semantic versioning. `~1.2` is equivalent to `>=1.2 <2.0`. For more details, read the next section below.
Caret Operator | `^1.2.3` | Very useful for projects that follow semantic versioning. `^1.2.3` is equivalent to `>=1.2.3 <2.0`. For more details, read the next section below.
### Next Significant Release (Tilde and Caret Operators)
The `~` operator is best explained by example: `~1.2` is equivalent to
`>=1.2 <2.0.0`, while `~1.2.3` is equivalent to `>=1.2.3 <1.3.0`. As you can see
it is mostly useful for projects respecting [semantic
versioning](http://semver.org/). A common usage would be to mark the minimum
minor version you depend on, like `~1.2` (which allows anything up to, but not
including, 2.0). Since in theory there should be no backwards compatibility
breaks until 2.0, that works well. Another way of looking at it is that using
`~` specifies a minimum version, but allows the last digit specified to go up.
The `^` operator behaves very similarly but it sticks closer to semantic
versioning, and will always allow non-breaking updates. For example `^1.2.3`
is equivalent to `>=1.2.3 <2.0.0` as none of the releases until 2.0 should
break backwards compatibility. For pre-1.0 versions it also acts with safety
in mind and treats `^0.3` as `>=0.3.0 <0.4.0`
> **Note:** Though `2.0-beta.1` is strictly before `2.0`, a version constraint
> like `~1.2` would not install it. As said above `~1.2` only means the `.2`
> can change but the `1.` part is fixed.
> **Note:** The `~` operator has an exception on its behavior for the major
> release number. This means for example that `~1` is the same as `~1.0` as
> it will not allow the major number to increase trying to keep backwards
> compatibility.
Version constraints can be specified in several ways, read
[versions](articles/versions.md) for more in-depth information on this topic.
### Stability
By default only stable releases are taken into consideration. If you would like
to also get RC, beta, alpha or dev versions of your dependencies you can do
so using [stability flags](04-schema.md#package-links). To change that for all
packages instead of doing per dependency you can also use the
By default only stable releases are taken into consideration. If you would
like to also get RC, beta, alpha or dev versions of your dependencies you can
do so using [stability flags](04-schema.md#package-links). To change that for
all packages instead of doing per dependency you can also use the
[minimum-stability](04-schema.md#minimum-stability) setting.
If you are using range comparisons when selecting non-stable packages, and you
@ -119,15 +87,15 @@ the `minimum-stability` setting and each package's stability flags.
### Test version constraints
You can test version constraints using [semver.mwl.be](http://semver.mwl.be). Fill in
a package name and it will autofill the default version constraint which Composer would add
to your `composer.json` file. You can adjust the version constraint and the tool will highlight
all releases that match.
You can test version constraints using [semver.mwl.be](http://semver.mwl.be).
Fill in a package name and it will autofill the default version constraint
which Composer would add to your `composer.json` file. You can adjust the
version constraint and the tool will highlight all releases that match.
## Installing Dependencies
To fetch the defined dependencies into your local project, just run the
`install` command of `composer.phar`.
To install the defined dependencies for your project, just run the
`install` command.
```sh
php composer.phar install
@ -139,11 +107,10 @@ It's a convention to put third party code into a directory named `vendor`.
In case of monolog it will put it into `vendor/monolog/monolog`.
> **Tip:** If you are using git for your project, you probably want to add
> `vendor` into your `.gitignore`. You really don't want to add all of that
> `vendor` in your `.gitignore`. You really don't want to add all of that
> code to your repository.
Another thing that the `install` command does is it adds a `composer.lock`
file into your project root.
You will notice the `install` command also created a `composer.lock` file.
## `composer.lock` - The Lock File
@ -151,72 +118,72 @@ After installing the dependencies, Composer writes the list of the exact
versions it installed into a `composer.lock` file. This locks the project
to those specific versions.
**Commit your application's `composer.lock` (along with `composer.json`) into version control.**
**Commit your application's `composer.lock` (along with `composer.json`)
into version control.**
This is important because the `install` command checks if a lock file is present,
and if it is, it downloads the versions specified there (regardless of what `composer.json`
says).
This is important because the `install` command checks if a lock file is
present, and if it is, it downloads the versions specified there (regardless
of what `composer.json` says).
This means that anyone who sets up the project will download the exact
same version of the dependencies. Your CI server, production machines, other
developers in your team, everything and everyone runs on the same dependencies, which
mitigates the potential for bugs affecting only some parts of the deployments. Even if you
develop alone, in six months when reinstalling the project you can feel confident the
dependencies installed are still working even if your dependencies released
many new versions since then.
This means that anyone who sets up the project will download the exact same
version of the dependencies. Your CI server, production machines, other
developers in your team, everything and everyone runs on the same dependencies,
which mitigates the potential for bugs affecting only some parts of the
deployments. Even if you develop alone, in six months when reinstalling the
project you can feel confident the dependencies installed are still working even
if your dependencies released many new versions since then.
If no `composer.lock` file exists, Composer will read the dependencies and
versions from `composer.json` and create the lock file after executing the `update` or the `install`
command.
versions from `composer.json` and create the lock file after executing the
`update` or the `install` command.
This means that if any of the dependencies get a new version, you won't get the updates
automatically. To update to the new version, use the `update` command. This will fetch
the latest matching versions (according to your `composer.json` file) and also update
the lock file with the new version.
This means that if any of the dependencies get a new version, you won't get the
updates automatically. To update to the new version, use the `update` command.
This will fetch the latest matching versions (according to your `composer.json`
file) and also update the lock file with the new version.
```sh
php composer.phar update
```
> **Note:** Composer will display a Warning when executing an `install` command if
`composer.lock` and `composer.json` are not synchronized.
> **Note:** Composer will display a Warning when executing an `install` command
> if `composer.lock` and `composer.json` are not synchronized.
If you only want to install or update one dependency, you can whitelist them:
```sh
php composer.phar update monolog/monolog [...]
```
> **Note:** For libraries it is not necessarily recommended to commit the lock file,
> see also: [Libraries - Lock file](02-libraries.md#lock-file).
> **Note:** For libraries it is not necessarily recommended to commit the lock
> file, see also: [Libraries - Lock file](02-libraries.md#lock-file).
## Packagist
[Packagist](https://packagist.org/) is the main Composer repository. A Composer
repository is basically a package source: a place where you can get packages
from. Packagist aims to be the central repository that everybody uses. This
means that you can automatically `require` any package that is available
there.
means that you can automatically `require` any package that is available there.
If you go to the [packagist website](https://packagist.org/) (packagist.org),
you can browse and search for packages.
Any open source project using Composer should publish their packages on
packagist. A library doesn't need to be on packagist to be used by Composer,
but it makes life quite a bit simpler.
packagist. A library doesn't need to be on packagist to be used by Composer, but
it makes life quite a bit simpler.
## Autoloading
For libraries that specify autoload information, Composer generates a
`vendor/autoload.php` file. You can simply include this file and you
will get autoloading for free.
`vendor/autoload.php` file. You can simply include this file and you will get
autoloading for free.
```php
require 'vendor/autoload.php';
```
This makes it really easy to use third party code. For example: If your
project depends on monolog, you can just start using classes from it, and they
will be autoloaded.
This makes it really easy to use third party code. For example: If your project
depends on monolog, you can just start using classes from it, and they will be
autoloaded.
```php
$log = new Monolog\Logger('name');
@ -243,8 +210,8 @@ You define a mapping from namespaces to directories. The `src` directory would
be in your project root, on the same level as `vendor` directory is. An example
filename would be `src/Foo.php` containing an `Acme\Foo` class.
After adding the `autoload` field, you have to re-run `dump-autoload` to re-generate
the `vendor/autoload.php` file.
After adding the `autoload` field, you have to re-run `dump-autoload` to
re-generate the `vendor/autoload.php` file.
Including that file will also return the autoloader instance, so you can store
the return value of the include call in a variable and add more namespaces.
@ -256,11 +223,11 @@ $loader->add('Acme\\Test\\', __DIR__);
```
In addition to PSR-4 autoloading, classmap is also supported. This allows
classes to be autoloaded even if they do not conform to PSR-4. See the
[autoload reference](04-schema.md#autoload) for more details.
classes to be autoloaded even if they do not conform to PSR-4. See the [autoload
reference](04-schema.md#autoload) for more details.
> **Note:** Composer provides its own autoloader. If you don't want to use
that one, you can just include `vendor/composer/autoload_*.php` files,
which return associative arrays allowing you to configure your own autoloader.
> **Note:** Composer provides its own autoloader. If you don't want to use that
> one, you can just include `vendor/composer/autoload_*.php` files, which return
> associative arrays allowing you to configure your own autoloader.
&larr; [Intro](00-intro.md) | [Libraries](02-libraries.md) &rarr;

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@ -0,0 +1,99 @@
<!--
tagline: The multitude of possibilities that are called version constraints.
-->
# Versions
## Basic Constraints
### Exact
You can specify the exact version of a package. This will tell Composer to
install this version and this version only. If other dependencies require
a different version, the solver will ultimately fail and abort any install
or update procedures.
Example: `1.0.2`
### Range
By using comparison operators you can specify ranges of valid versions. Valid
operators are `>`, `>=`, `<`, `<=`, `!=`. <br />You can define multiple ranges.
Ranges separated by a space (<code> </code>) or comma (`,`) will be treated as
a **logical AND**. A double pipe (<code>&#124;&#124;</code>) will be treated as
a **logical OR**. AND has higher precedence than OR.
Example: `>=1.0` `>=1.0 <2.0` `>=1.0 <1.1 || >=1.2`
### Range (Hyphen)
Inclusive set of versions. Partial versions on the right include are completed
with a wildcard. For example `1.0 - 2.0` is equivalent to `>=1.0.0 <2.1` as the
`2.0` becomes `2.0.*`. On the other hand `1.0.0 - 2.1.0` is equivalent to
`>=1.0.0 <=2.1.0`.
Example: `1.0 - 2.0`
### Wildcard
You can specify a pattern with a `*` wildcard. `1.0.*` is the equivalent of
`>=1.0 <1.1`.
Example: `1.0.*`
## Next Significant Release Operators
### Tilde
The `~` operator is best explained by example: `~1.2` is equivalent to
`>=1.2 <2.0.0`, while `~1.2.3` is equivalent to `>=1.2.3 <1.3.0`. As you can see
it is mostly useful for projects respecting [semantic
versioning](http://semver.org/). A common usage would be to mark the minimum
minor version you depend on, like `~1.2` (which allows anything up to, but not
including, 2.0). Since in theory there should be no backwards compatibility
breaks until 2.0, that works well. Another way of looking at it is that using
`~` specifies a minimum version, but allows the last digit specified to go up.
Example: `~1.2`
> **Note:** Though `2.0-beta.1` is strictly before `2.0`, a version constraint
> like `~1.2` would not install it. As said above `~1.2` only means the `.2`
> can change but the `1.` part is fixed.
> **Note:** The `~` operator has an exception on its behavior for the major
> release number. This means for example that `~1` is the same as `~1.0` as
> it will not allow the major number to increase trying to keep backwards
> compatibility.
### Caret
The `^` operator behaves very similarly but it sticks closer to semantic
versioning, and will always allow non-breaking updates. For example `^1.2.3`
is equivalent to `>=1.2.3 <2.0.0` as none of the releases until 2.0 should
break backwards compatibility. For pre-1.0 versions it also acts with safety
in mind and treats `^0.3` as `>=0.3.0 <0.4.0`.
Example: `^1.2.3`
## Stability
If you are using a constraint that does not explicitly define a stability,
Composer will default interally to `-dev` or `-stable`, depending on the
operator(s) used. This happens transparently.
If you wish to explicitly consider only the stable release in the comparison,
add the suffix `-stable`.
Examples:
Constraint | Internally
----------------------------------------------
`1.2.3` | `=1.2.3.0-stable`
`>1.2` | `>1.2.0.0-stable`
`>=1.2` | `>=1.2.0.0-dev`
`>=1.2-stable` | `>=1.2.0.0-stable`
`<1.3` | `<1.3.0.0-dev`
`<=1.3` | `<=1.3.0.0-stable`
`1 - 2` | `>=1.0.0.0-dev <3.0.0.0-dev`
`~1.3` | `>=1.3.0.0-dev <2.0.0.0-dev`
`1.4.*` | `>=1.4.0.0-dev <1.5.0.0-dev`