New in Symfony 2.6: Farewell to ICU component
If you are a Symfony developer, you have probably suffered the infamous intl problem when installing or deploying Symfony applications. The following error message is the usual symptom of suffering this problem:
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Installing dependencies (including require-dev) from lock file Your requirements could not be resolved to an installable set of packages. Problem 1 - Installation request for symfony/icu v1.2.x -> satisfiable by symfony/icu[v1.2.x]. - symfony/icu v1.2.x requires lib-icu >=4.4 -> the requested linked library icu has the wrong version installed or is missing from your system, make sure to have the extension providing it. Problem 2 - symfony/icu v1.2.x requires lib-icu >=4.4 -> the requested linked library icu has the wrong version installed or is missing from your system, make sure to have the extension providing it. - symfony/intl v2.5.0 requires symfony/icu ~1.0-RC -> satisfiable by symfony/icu[v1.2.x]. - Installation request for symfony/intl v2.5.0 -> satisfiable by symfony/intl[v2.5.0].
The good news is that in Symfony 2.6 this problem is gone forever. It doesn't matter the way you installed PHP or your specific operating system, you will never see this error again. Moreover, as this problem is so annoying, we've decided to backport it to previous Symfony versions. This means that you won't see this problem again in the new versions of Symfony 2.3 and 2.5. The issue will remain in Symfony 2.4, because that branch is no longer maintained.
"The big picture" of Symfony internationalization¶
To better understand the cause of this problem and its solution, it's important to understand The Big Picture of the projects and systems involved:
- The CLDR project collects and maintains internationalization data, such as country and language names, currency metadata, number formats, postal code and phone number formats. CLDR data is used in all smartphones, operating systems and important software applications developed by companies such as Apple, Google, Microsoft and IBM.
- The ICU project uses the CLDR data and builds C and Java classes on top of
them, such as
- The PHP intl extension makes some ICU classes accessible in PHP, but it does not bundle the CLDR data. It uses the data installed globally on the system (which is independent of PHP).
- The Symfony Icu component includes all the CLDR data, because Symfony needs
access to the data in all locales, independent of the system's configuration.
We even offered different versions: if you didn't have the
intlextension installed, you'd have Icu
1.0.x, which ships the data as
.phpfiles. With the
intlextension, you'd have
1.2.xwhich ships the data as binary files, readable using the
- The Symfony Intl component does two things: first, it provides access to
the data of the Icu component (
Intl::get*Bundle()->get*()). Second, it provides a partial PHP implementation for some ICU classes (
NumberFormatter) which you can use when
intlextension is not installed.
Understanding the problem¶
As you may know, Composer uses two files called
to manage your project's dependencies. The
composer.lock file stores the
hashes of the package versions you have installed.
The workflow that causes this problem is usually the following:
- Developer A, who has the
intlextension, installs or updates Symfony.
composer.lockfile will contain the Icu
- Developer A commits the
composer.lockfile to the repository.
- Developer B, who doesn't have the
intlextension, installs the project with the usual
- Composer tries to install Icu
1.2.x, which requires
intl, and the result is the infamous symfony/icu v1.2.x requires lib-icu >=4.4 error.
- If Developer B executes
composer updatecommand, Composer will correctly detect that
intlis not installed and it will use instead Icu
Understanding the solution¶
In order to solve this problem, the Intl component now includes all the CLDR data. As a consequence, the Icu component has been deprecated because is no longer needed.
Moreover, when you didn't have the
intl extension installed, previously you
could only access to the CLDR data in English. Now, you can access to all data
in all locales, independent of whether
intl is installed or not.
Given the large amount of information contained in the CLDR data, you may be worried by the impact in the total Symfony download size. Even if the data is stored as JSON files instead of using a binary format, the total compressed size is just about 2 MB.
Note Most of the contents of this post have been written by Bernhard Schussek, who kindly explained me all the pieces involved in the Symfony internationalization sub-framework.
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