rfc:batch_use_declarations

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rfc:batch_use_declarations [2015/01/29 16:31] – fix some code samples that had duplicated use statements marciorfc:batch_use_declarations [2015/01/29 23:16] – moved page marcio
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-====== PHP RFC: Batch Use Declarations ====== +Moved to https://wiki.php.net/rfc/group_use_declarations
-  * Date: 2015-01-28 +
-  * Author: Márcio Almada, marcio.web2@gmail.com +
-  * Status: Draft +
-  * First Published at: http://wiki.php.net/rfc/batch_use_declarations +
-  * Patch: https://github.com/php/php-src/pull/1005 +
- +
-===== Introduction ===== +
-This RFC represents an attempt to improve current PHP namespace implementation by introducing the concept of **Batch Use Declarations**: +
- +
-<code php> +
-// Proposed batch use syntax: +
- +
-use FooLibrary\Bar\Baz\Biz { ClassA, ClassB, ClassC as Fizbo, ClassD }; +
- +
-// Compared to current use syntax: +
- +
-use FooLibrary\Bar\Baz\Biz\ClassA; +
-use FooLibrary\Bar\Baz\Biz\ClassB; +
-use FooLibrary\Bar\Baz\Biz\ClassC as Fizbo; +
-use FooLibrary\Bar\Baz\Biz\ClassD; +
-</code> +
- +
-===== Proposal ===== +
-Batch use declarations, also known as **grouped imports**, are just **syntax sugar** to cut verbosity when importing multiple entities from a common namespace. Using common PHP library examples, the following use declarations are equivalents: +
- +
-<code php> +
-// Current use syntax: +
- +
-use Doctrine\Common\Collections\Expr\Comparison; +
-use Doctrine\Common\Collections\Expr\Value; +
-use Doctrine\Common\Collections\Expr\CompositeExpression; +
- +
-// Proposed batch use syntax: +
- +
-use Doctrine\Common\Collections\Expr { Comparison, Value, CompositeExpression }; +
-</code> +
- +
-=== Compound Namespaces === +
-Compound namespaces are also allowed. For instance, the following use declarations are equivalents: +
- +
-<code php> +
-// Current use syntax: +
- +
-use Symfony\Component\Console\Helper\Table; +
-use Symfony\Component\Console\Input\ArrayInput; +
-use Symfony\Component\Console\Output\NullOutput; +
-use Symfony\Component\Console\Question\Question; +
-use Symfony\Component\Console\Input\InputInterface; +
-use Symfony\Component\Console\Output\OutputInterface; +
-use Symfony\Component\Console\Question\ChoiceQuestion as Choice; +
-use Symfony\Component\Console\Question\ConfirmationQuestion; +
- +
-// Proposed batch use syntax: +
- +
-use Symfony\Component\Console { +
-  Helper\Table, +
-  Input\ArrayInput, +
-  Input\InputInterface, +
-  Output\NullOutput, +
-  Output\OutputInterface, +
-  Question\Question, +
-  Question\ChoiceQuestion as Choice, +
-  Question\ConfirmationQuestion, +
-}; +
-</code> +
- +
-This is also a real use case. Check out the Laravel source code: +
- +
-  * [[https://github.com/laravel/framework/blob/5afdac39290bc38d729830190f17581b60b08502/src/Illuminate/Console/Command.php#L3-L10|https://github.com/laravel/framework/blob/4.2/src/Illuminate/Console/Command.php#L3-L10]] +
-  * [[https://github.com/laravel/framework/blob/5afdac39290bc38d729830190f17581b60b08502/src/Illuminate/Log/Writer.php#L5-L9|https://github.com/laravel/framework/blob/4.2/src/Illuminate/Log/Writer.php#L5-L9]] +
- +
-=== Non Mixed Use Declarations === +
-As expected, non mixed batch use declarations are supported: +
- +
-<code php> +
-// Current use syntax: +
- +
-use function foo\math\sin, foo\math\cos, foo\math\cosh; +
-use const    foo\math\PI, foo\math\E, foo\math\GAMMA, foo\math\GOLDEN_RATIO; +
- +
-// Proposed non mixed batch use syntax: +
- +
-use function foo\math { sin, cos, cosh }; +
-use const    foo\math { PI, E, GAMMA, GOLDEN_RATIO }; +
-</code> +
- +
-=== Mixed Use Declarations === +
-Current namespace implementation does not allow mixed imports of functions, constants and classes. With the approval of this RFC, for completeness, the following hypothetical mixed imports would be possible: +
- +
-<code php> +
-// Current use syntax: +
- +
-use          foo\math\Math; +
-use const    foo\math\PI; +
-use function foo\math\sin, foo\math\cos, foo\math\cosh; +
- +
-// Proposed mixed batch use syntax: +
- +
-use foo\math { Math, const PI, function sin, function cos, function cosh }; +
- +
-</code> +
- +
-===== About The Syntax Choice ===== +
-The current choice for batch use syntax is basically a small variation from the current trait adaptation syntax: +
- +
-<code php> +
-use A, B { +
-    B::smallTalk insteadof A; +
-    A::bigTalk insteadof B; +
-} +
-</code> +
- +
-Such design choice allows the feature to stay familiar and intuitive to most PHP user base. +
- +
-===== Optional: Nested Batch Use Declarations ===== +
-**Nesting** would allow the following use case: +
- +
-<code php> +
-use Symfony\Component\Console { +
-  Helper\Table, +
-  Input { ArrayInput, InputInterface } +
-  Output { NullOutput, OutputInterface }, +
-  Question { Question, ChoiceQuestion, ConfirmationQuestion } +
-}; +
-</code> +
- +
-As the author of this RFC, I consider the **nesting** option **too complex** to be introduced. But since many people mentioned this **possibility**, it will be put into the discussion so the community has a chance to appoint. +
- +
-===== Backward Incompatible Changes ===== +
-There is no BC breaks with current implementation or feature concepts. +
- +
-===== Proposed PHP Version(s) ===== +
-This is proposed for the next PHP x, which at the time of this writing would be PHP 7.  +
- +
-===== RFC Impact ===== +
- +
-=== On Backward Compatibility === +
-This RFC is backwards compatible with previous PHP releases. +
- +
-===== Open Issues ===== +
-  * Should nested batch use declarations be allowed? +
- +
-===== Unaffected PHP Functionality ===== +
-Original namespace implementation is not affected by the addition of batch use declarations. Current syntax would still be valid. +
- +
-===== Proposed Voting Choices ===== +
-As this RFC represents a language change a two third majority is required.  +
- +
-===== Patches and Tests ===== +
-The implementation aims to be minimal and of easy maintenance. I created a PR so that the patch diff can be viewed easily: https://github.com/php/php-src/pull/1005 +
- +
-The current initial implementation can be found on my PHP [[https://github.com/marcioAlmada/php-src/tree/batch-use|fork]]. You can also directly contribute to this RFC by sending a pull request to https://github.com/marcioAlmada/RFCs. +
- +
-===== References ===== +
-There is no found record related to batch use declarations on mailing lists. +
- +
-==== Support in other languages ==== +
-Other languages have similar ways to import multiple entities from a given package or module: +
- +
-  * [[http://www.rust-lang.org|Rust Language]] has a very similar sintax `use a::b::{c,d,e,f};` +
-  * [[https://www.python.org|Pyhon]] has a different syntax but with the same objective: `from fibo import fib, fib2, fib3` +
- +
-===== Rejected Features ===== +
-Awaiting discussion. +
rfc/batch_use_declarations.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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