rfc:group_use_declarations

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rfc:group_use_declarations [2015/02/09 08:08] – disambiguate a setence marciorfc:group_use_declarations [2017/09/22 13:28] (current) – external edit 127.0.0.1
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   * Date: 2015-01-28   * Date: 2015-01-28
   * Author: Márcio Almada, marcio.web2@gmail.com   * Author: Márcio Almada, marcio.web2@gmail.com
-  * Status: Under Discussion+  * Status: Implemented (in PHP 7.0)
   * First Published at: http://wiki.php.net/rfc/group_use_declarations   * First Published at: http://wiki.php.net/rfc/group_use_declarations
   * Patch: https://github.com/php/php-src/pull/1005   * Patch: https://github.com/php/php-src/pull/1005
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 ===== Proposal ===== ===== Proposal =====
-Group use declarations 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:+Group use declarations are used to cut verbosity when importing multiple entities from a common namespace. Using common PHP library examples, the following use declarations are equivalents:
  
 <code php> <code php>
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 ===== Justification ===== ===== Justification =====
  
-Group use statements makes it easier to identify that multiple imported entities are from the same module. For the first example in this RFC, instead of having to read 'FooLibrary\Bar\Baz\Biz' four times to see that the namespace is the same for each entry, it is clear by the grouping syntax that the entries all come from the same namespace.+Group use declaratations facilitates to import multiple structures from a common namespace and cuts a good level of verbosity in most cases. Group use declaratations makes it easier to identify that multiple imported entities belong to the same module.
  
-Also, group use statements makes it easier to see in patch diffs that a dependency on a new module has been introduced. For instance, a patch that adds a new dependency on "Consolidation" namespace has been introduced:+For the first example in this RFC, instead of having to read 'FooLibrary\Bar\Baz\Biz' four times to see that the namespace is the same for each entry, it is clear by the grouping syntax that the entries all come from the same namespace. 
 + 
 +The same advantage regardless readability is noticeable on patch diffs that a dependency on a new module has been introduced. For instance, a patch that adds a new dependency on "Consolidation" namespace has been introduced:
  
 <code> <code>
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 use Symfony\Component\Console\Question\{ use Symfony\Component\Console\Question\{
     ConfirmationQuestion,     ConfirmationQuestion,
-    ChoiceQuestion as Choice;+    ChoiceQuestion as Choice,
 +   OptionQuestion, +   OptionQuestion,
     Question,     Question,
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   * The search for literal full qualified namespaces can become less straightforward.   * The search for literal full qualified namespaces can become less straightforward.
  
-===== About The Syntax Choice =====+==== About The Syntax Choice ====
 The syntax chosen is inline with the current [[http://php.net/traits|trait adaptation]] syntax to make it look and feel similar to existing PHP standards. Such design choice allows the feature to stay familiar and intuitive to most PHP user base. The syntax chosen is inline with the current [[http://php.net/traits|trait adaptation]] syntax to make it look and feel similar to existing PHP standards. Such design choice allows the feature to stay familiar and intuitive to most PHP user base.
  
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 This shall be addressed on voting phase: should a trailing "\" be enforced or removed from syntax? This shall be addressed on voting phase: should a trailing "\" be enforced or removed from syntax?
- 
-===== Backward Incompatible Changes ===== 
-There is no BC breaks with current implementation or feature concepts. 
  
 ===== Proposed PHP Version(s) ===== ===== Proposed PHP Version(s) =====
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 ===== RFC Impact ===== ===== RFC Impact =====
 +
 +=== On Functional Programming / Autoloading ===
 +
 +Group use declarations is also very helpful for the PHP user base more fond to the **functional** programming paradigms. This RFC would be especially important if PHP finally gets **function autoloading**.
 +
 +Currently, sets of independent functions have to be implemented as static classes. But with function autoloading, they’d have to be imported independently, and that would lead to way too many use statements without this feature. Here is an example to illustrate this impact using the well known Nikita's [[https://github.com/nikic/iter|iter]] functional library:
 +
 +<code php>
 +// Current use syntax:
 +
 +use function iter\range;
 +use function iter\map;
 +use function iter\filter;
 +use function iter\apply;
 +use function iter\reduce;
 +use function iter\fn\operator;
 +
 +// Proposed syntax:
 +
 +use function iter\{ range, map, filter, apply, reduce, fn\operator };
 +
 +</code>
  
 === On Backward Compatibility === === On Backward Compatibility ===
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 Original namespace implementation is not affected by the addition of group use declarations. Current syntax would still be valid. Original namespace implementation is not affected by the addition of group use declarations. Current syntax would still be valid.
  
-===== Proposed Voting Choices ===== +===== Support in other languages ===== 
-As this RFC represents a language change a 2/3 majority is required. +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 syntax ''use a::b::{c, d, e, f};'' 
 +  * [[http://www.scala-lang.org/old/node/119|Scala]] has a very similar syntax ''use a.b.{c, d, e, f};'' 
 +  * [[https://www.python.org|Python]] has a different syntax but with the same objective: ''from fibo import fib, fib2, fib3'' 
 + 
 +===== Votes ===== 
 +As this is a language change, this RFC requires a 2/3 majority of Yes votes (with or without trailing "\") to pass. Voting started on 2015-02-11 and will end on 2015-02-25. 
 + 
 +<doodle title="Should Grouped Use Declarations be added to PHP 7" auth="marcio" voteType="single" closed="true"> 
 +   * Yes - **with** a trailing "\" 
 +   * Yes - **without** a trailing "\" 
 +   * No 
 +</doodle> 
 + 
 +===== Discussion in a Nutshell ===== 
 + 
 +In case you missed the discussion. This section lists the common counter points towards this RFC and how they were replied by the RFC author and supporters on mailing lists and media: 
 + 
 +==== My IDE already does the imports for me and folds the namespaces so I don't need this feature ==== 
 + 
 +We should create **usable languages by design** rather than **languages only usable by tooling**. Tooling can be very important 
 +but the moment you notice a stack of tools is needed to have a reasonable experience and readability with a programming language then something needs to be improved. 
 + 
 +A programming language should be able stand on its own and not require IDE assistance for reasonable use. That's what this RFC does, it brings a very common feature already available in many languages employing some kind of namespacing. 
 + 
 +==== The RFC encourages violation of the the SRP and other best practices ==== 
 + 
 +This is **not true**. Nikita already wrote a great response to this on the official PHP mailing list. Beware of the slay of good argumentation ahead: http://news.php.net/php.internals/82622 
 + 
 +==== We should have "first class packages" first, therefore we can't approve this RFC now! ==== 
 + 
 +This is painfully illogic. Group use declarations and "first class packages" are completely orthogonal features. Having group use declarations will only help to support long awaited features like "first class namespaces" or "function autoloading". The order in which the features are proposed or accepted is irrelevant in this case. We can **have** the feature **now**. 
 + 
 +Doing so **prior** to a major PHP7 **release** is, in fact, the **best hour** to **approve** this RFC. 
 + 
 +==== We should go for Python's syntax instead and reject this RFC ==== 
 + 
 +I doubt Python syntax will ever be proposed for PHP because it would require the the **from** keyword to be reserved, hence one of the reasons it was discarded during research and discussion. Other reason is that the glob brace syntax is more tailored for PHP and it is a [[https://wiki.php.net/rfc/group_use_declarations#support_in_other_languages|good choice]]. 
  
 ===== Patches and Tests ===== ===== Patches and Tests =====
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 ===== References ===== ===== References =====
 There is no found record related to group use declarations on mailing lists. There is no found record related to group 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 syntax `use a::b::{c, d, e, f};` 
-  * [[http://www.scala-lang.org/old/node/119|Scala]] has a very similar syntax `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` 
  
 ===== Changelog ===== ===== Changelog =====
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   * 0.1 - first proposal   * 0.1 - first proposal
   * 0.2 - added trailing "\" syntax to proposal   * 0.2 - added trailing "\" syntax to proposal
-  * 0.3 - added voting option for a non trialling "\" syntax+  * 0.3 - added voting option for a non trailing "\" syntax
   * 0.4 - RFC was simplified: "nesting" voting option was removed   * 0.4 - RFC was simplified: "nesting" voting option was removed
 +
 +===== Acknowledgements =====
 +
 +Thanks to:
 +
 +  - Daniel Ackroyd for reviewing this RFC.
 +  - Andrea and Rangad for their insightful opinions.
 +  - NikiC for providing accurate information about the PHP implementation.
 +  - All people on http://chat.stackoverflow.com/rooms/11/php
  
rfc/group_use_declarations.1423469290.txt.gz · Last modified: 2017/09/22 13:28 (external edit)

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