5 Composer tips that PHP developers should know, developer composer

Composer is a new generation of PHP dependency management tool. For its introduction and basic usage, you can read this article "A New Era of Composer PHP Dependency Management". This article introduces five tips for using Composer, hoping to bring convenience to your PHP development.

1. Only update a single library

You only want to update a specific library and don’t want to update all its dependencies. It’s very simple:

composer update foo/bar

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In addition, this trick can also be used to solve the "warning message problem". You must have seen warning messages like this:

<code>Warning: The lock file is not up to date with the latest changes in composer.json, you may be getting outdated dependencies, run update to update them. 
</code>

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Damn, what went wrong? Don't panic! If you edit composer.json, you should see a message like this. For example, if you add or update details such as a library description, author, more parameters, or even just a space, it will change the md5sum of the file. Then Composer will warn you that the hash value is different from the one recorded in composer.lock.

So what should we do? The update command can update the lock file, but if you only add some descriptions, it should not update any libraries. In this case, just update nothing:

$ composer update nothing
Loading composer repositories with package information 
Updating dependencies 
Nothing to install or update 
Writing lock file 
Generating autoload files

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This way, Composer will not update the library, but it will update composer.lock. Note that nothing is not a keyword of the update command. There is just no nothing result caused by this package. If you type foobar, the result will be the same.

If the Composer version you are using is new enough, you can use the --lock option directly:

composer update --lock

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2. Install the library without editing `composer.json`

You may find it too troublesome to modify composer.json every time you install a library, then you can use the require command directly.

composer require "foo/bar:1.0.0"

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This method can also be used to quickly open a new project. The init command has the --require option, which can automatically write composer.json: (note that we use -n so that we don’t have to answer the question)

$ composer init --require=foo/bar:1.0.0 -n
$ cat composer.json
{
  "require": {
    "foo/bar": "1.0.0"
  }
}

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3. Derivation is easy

Have you tried the create-project command during initialization?

composer create-project doctrine/orm path 2.2.0

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This will automatically clone the repository and check out the specified version. This command is very convenient to use when cloning a library, as there is no need to search for the original URI.

4. Consider caching, `dist`packet priority

Composer from the past year will automatically archive the dist packages you downloaded. By default, the dist package is used for tagged versions, such as "symfony/symfony": "v2.1.4", or wildcards or version ranges, "2.1.*" or ">=2.2,<2.3-dev" (if you use stable as your minimum-stability).

The

dist package can also be used for branches such as dev-master. Github allows you to download the compressed package of a certain git reference. To force the use of a tarball instead of cloning the source code, you can use the install option of update and --prefer-dist.

Here is an example (I used the --profile option to show execution time):

$ composer init --require="twig/twig:1.*" -n --profile
Memory usage: 3.94MB (peak: 4.08MB), time: 0s

$ composer install --profile
Loading composer repositories with package information 
Installing dependencies 
 - Installing twig/twig (v1.12.2)
  Downloading: 100%

Writing lock file 
Generating autoload files 
Memory usage: 10.13MB (peak: 12.65MB), time: 4.71s

$ rm -rf vendor

$ composer install --profile
Loading composer repositories with package information 
Installing dependencies from lock file 
 - Installing twig/twig (v1.12.2)
  Loading from cache

Generating autoload files 
Memory usage: 4.96MB (peak: 5.57MB), time: 0.45s

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Here, the compressed package of twig/twig:1.12.2 is saved in ~/.composer/cache/files/twig/twig/1.12.2.0-v1.12.2.zip. Use it directly when reinstalling the package.

5. If you want to modify, the source code should be given priority

When you need to modify the library, cloning the source code is more convenient than downloading the package. You can use --prefer-source to force selection of cloned source code.

composer update symfony/yaml --prefer-source

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Next you can modify the file:

composer status -v 
You have changes in the following dependencies: 
/path/to/app/vendor/symfony/yaml/Symfony/Component/Yaml:
  M Dumper.php

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When you try to update a modified library, Composer will remind you and ask whether to abandon the modification:

$ composer update
Loading composer repositories with package information 
Updating dependencies 
 - Updating symfony/symfony v2.2.0 (v2.2.0- => v2.2.0)
  The package has modified files:
  M Dumper.php
  Discard changes [y,n,v,s,&#63;]&#63;

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Prepare for production environment

Finally, when deploying code to the production environment, don’t forget to optimize automatic loading:

composer dump-autoload --optimize

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You can also use --optimize-autoloader when installing packages. Without this option, you may see a 20% to 25% performance loss.

If you need help or want to know the details of a certain command, you can read the official documentation or Chinese documentation, or check out this interactive cheat sheet made by JoliCode.

Original address: 5 features to know about Composer PHP
Translation address: 5 Composer tips that PHP developers should know

1. Only update a single library

You only want to update a specific library and don’t want to update all its dependencies. It’s very simple:

composer update foo/bar

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In addition, this trick can also be used to solve the "warning message problem". You must have seen warning messages like this:

<code>Warning: The lock file is not up to date with the latest changes in composer.json, you may be getting outdated dependencies, run update to update them. 
</code>

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擦，哪里出问题了？别惊慌！如果你编辑了composer.json，你应该会看到这样的信息。比如，如果你增加或更新了细节信息，比如库的描述、作者、更多参数，甚至仅仅增加了一个空格，都会改变文件的md5sum。然后Composer就会警告你哈希值和composer.lock中记载的不同。

那么我们该怎么办呢？update命令可以更新lock文件，但是如果仅仅增加了一些描述，应该是不打算更新任何库。这种情况下，只需update nothing：

$ composer update nothing
Loading composer repositories with package information 
Updating dependencies 
Nothing to install or update 
Writing lock file 
Generating autoload files

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这样一来，Composer不会更新库，但是会更新composer.lock。注意nothing并不是update命令的关键字。只是没有nothing 这个包导致的结果。如果你输入foobar，结果也一样。

如果你用的Composer版本足够新，那么你可以直接使用--lock选项：

composer update --lock

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2. 不编辑`composer.json`的情况下安装库

你可能会觉得每安装一个库都需要修改composer.json太麻烦，那么你可以直接使用require命令。

composer require "foo/bar:1.0.0"

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这个方法也可以用来快速地新开一个项目。init命令有--require选项，可以自动编写composer.json：（注意我们使用-n，这样就不用回答问题）

$ composer init --require=foo/bar:1.0.0 -n
$ cat composer.json
{
  "require": {
    "foo/bar": "1.0.0"
  }
}

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3. 派生很容易

初始化的时候，你试过create-project命令么？

composer create-project doctrine/orm path 2.2.0

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这会自动克隆仓库，并检出指定的版本。克隆库的时候用这个命令很方便，不需要搜寻原始的URI了。

4. 考虑缓存，`dist`包优先

最近一年以来的Composer会自动存档你下载的dist包。默认设置下，dist包用于加了tag的版本，例如"symfony/symfony": "v2.1.4"，或者是通配符或版本区间，"2.1.*"或">=2.2,<2.3-dev"（如果你使用stable作为你的minimum-stability）。

dist包也可以用于诸如dev-master之类的分支，Github允许你下载某个git引用的压缩包。为了强制使用压缩包，而不是克隆源代码，你可以使用install和update的--prefer-dist选项。

下面是一个例子（我使用了--profile选项来显示执行时间）：

$ composer init --require="twig/twig:1.*" -n --profile
Memory usage: 3.94MB (peak: 4.08MB), time: 0s

$ composer install --profile
Loading composer repositories with package information 
Installing dependencies 
 - Installing twig/twig (v1.12.2)
  Downloading: 100%

Writing lock file 
Generating autoload files 
Memory usage: 10.13MB (peak: 12.65MB), time: 4.71s

$ rm -rf vendor

$ composer install --profile
Loading composer repositories with package information 
Installing dependencies from lock file 
 - Installing twig/twig (v1.12.2)
  Loading from cache

Generating autoload files 
Memory usage: 4.96MB (peak: 5.57MB), time: 0.45s

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这里，twig/twig:1.12.2的压缩包被保存在~/.composer/cache/files/twig/twig/1.12.2.0-v1.12.2.zip。重新安装包时直接使用。

5. 若要修改，源代码优先

当你需要修改库的时候，克隆源代码就比下载包方便了。你可以使用--prefer-source来强制选择克隆源代码。

composer update symfony/yaml --prefer-source

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接下来你可以修改文件：

composer status -v 
You have changes in the following dependencies: 
/path/to/app/vendor/symfony/yaml/Symfony/Component/Yaml:
  M Dumper.php

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当你试图更新一个修改过的库的时候，Composer会提醒你，询问是否放弃修改：

$ composer update
Loading composer repositories with package information 
Updating dependencies 
 - Updating symfony/symfony v2.2.0 (v2.2.0- => v2.2.0)
  The package has modified files:
  M Dumper.php
  Discard changes [y,n,v,s,&#63;]&#63;

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