rfc:short-functions

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rfc:short-functions [2021/03/26 12:14] – Fixes typo on code snippet nunomadurorfc:short-functions [2021/06/15 22:29] (current) – Fix RFC status ilutov
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   * Date: 2020-10-20   * Date: 2020-10-20
   * Author: Larry Garfield (larry@garfieldtech.com)   * Author: Larry Garfield (larry@garfieldtech.com)
-  * Status: Draft +  * Status: Declined 
-  * First Published at: http://wiki.php.net/rfc/short-functions+  *  First Published at: http://wiki.php.net/rfc/short-functions
  
 ===== Introduction ===== ===== Introduction =====
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 This RFC is designed to complement the [[rfc:auto-capture-closure|Auto-capturing multi-statement closures]] RFC.  Both stand on their own and offer independent benefits.  However, they have been designed such that their syntax is complementary and consistent.  Specifically: This RFC is designed to complement the [[rfc:auto-capture-closure|Auto-capturing multi-statement closures]] RFC.  Both stand on their own and offer independent benefits.  However, they have been designed such that their syntax is complementary and consistent.  Specifically:
- 
  
   * The ''=>'' sigil always means "evaluates to the expression on the right," in all circumstances.  (Named functions, anonymous functions, arrays, and ''match()''.)   * The ''=>'' sigil always means "evaluates to the expression on the right," in all circumstances.  (Named functions, anonymous functions, arrays, and ''match()''.)
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 Expressions are becoming increasingly capable, too.  match() expressions and throw expressions in PHP 8.0, plus proposals such as [[rfc:pipe-operator-v2|PHP RFC: Pipe Operator v2]], are collectively making it easier to write expressive expressions.  Enumeration methods are likely to consist primarily of a single match() statement.  This improvement is a part of that larger trend. Expressions are becoming increasingly capable, too.  match() expressions and throw expressions in PHP 8.0, plus proposals such as [[rfc:pipe-operator-v2|PHP RFC: Pipe Operator v2]], are collectively making it easier to write expressive expressions.  Enumeration methods are likely to consist primarily of a single match() statement.  This improvement is a part of that larger trend.
  
-=== Pure functions ===+The trend in PHP in recent years has been toward more compact but still readable syntax that eliminates redundancy.  Property promotion, arrow functions, the nullsafe operator, and similar recent well-received additions demonstrate this trend.  This RFC seeks to continue that trend to make PHP more pleasant to write while still being just as clear to read. 
 + 
 +==== Pure functions ====
  
 Expression functions are also more likely to be pure, and thus avoid mutable state.  That cannot be guaranteed as it is possible to write single-expression functions that "leak" via global variables, like so: Expression functions are also more likely to be pure, and thus avoid mutable state.  That cannot be guaranteed as it is possible to write single-expression functions that "leak" via global variables, like so:
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 However, such code would be readily apparent as using global mutable state, and is easily avoided.  That makes short-functions more reliably "safe" and thus less prone to stateful errors. However, such code would be readily apparent as using global mutable state, and is easily avoided.  That makes short-functions more reliably "safe" and thus less prone to stateful errors.
  
-==== Examples ====+===== Examples =====
  
 Below are some examples of "long form" current code and what the short function equivalent would be.  This RFC asserts that the shorter version is more concise and readable.  All code is using standard PSR-12 formatting. Below are some examples of "long form" current code and what the short function equivalent would be.  This RFC asserts that the shorter version is more concise and readable.  All code is using standard PSR-12 formatting.
  
-=== Match functions ===+==== Match functions ====
  
 A function that encapsulates a match() expression. A function that encapsulates a match() expression.
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 </code> </code>
  
-=== Enum methods ===+==== Enum methods ====
  
 In practice, most enum methods are likely to contain only a match expression, the evaluated value of which should be returned.  That makes them a good candidate for short functions and eliminating visual clutter. In practice, most enum methods are likely to contain only a match expression, the evaluated value of which should be returned.  That makes them a good candidate for short functions and eliminating visual clutter.
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 </code> </code>
  
-=== Getter methods ===+==== Getter methods ====
  
-Many classes consist primarily or almost entirely out of methods that either return a property, or some computation off of a property.  With short-functions, that becomes considerably more concise.+Many classes consist primarily or almost entirely of methods that either return a property, or some computation off of a property.  With short-functions, that becomes considerably more concise.
  
 <code php> <code php>
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 </code> </code>
  
-=== Functional code ===+==== Functional code ====
  
 <code php> <code php>
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 </code> </code>
  
-=== Conditional methods ===+==== Conditional methods ====
  
 A common refactoring technique is to take a complex conditional in an if statement and move it to its own method, so it can be given a self-descriptive name.  Such methods are naturally single-expression.  Thus, well-factored code is likely to have a large percentage of its functions and methods be single-expression, and thus candidates for short functions. A common refactoring technique is to take a complex conditional in an if statement and move it to its own method, so it can be given a self-descriptive name.  Such methods are naturally single-expression.  Thus, well-factored code is likely to have a large percentage of its functions and methods be single-expression, and thus candidates for short functions.
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 Which is more simple and compact than a full function body. Which is more simple and compact than a full function body.
  
-=== Decorating functions in live code ===+==== Decorating functions in live code ====
  
 Often times, methods exist that are just delegating to some other method, either in the same object or a composed object.  These are also good candidates for a more compact syntax.  For example, here's some code pulled from the Drupal database layer's Select query builder.  (These are all real methods; I've just stripped out the comments and converted them to PSR-12 style.) Often times, methods exist that are just delegating to some other method, either in the same object or a composed object.  These are also good candidates for a more compact syntax.  For example, here's some code pulled from the Drupal database layer's Select query builder.  (These are all real methods; I've just stripped out the comments and converted them to PSR-12 style.)
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 The use of the ''fn'' keyword was also considered, but rejected.  In context, ''fn'' currently indicates that auto-capture will happen for variables from the lexical scope.  (See the discussion above.)  However, a named function has no meaningful values to capture, making ''function'' more appropriate. The use of the ''fn'' keyword was also considered, but rejected.  In context, ''fn'' currently indicates that auto-capture will happen for variables from the lexical scope.  (See the discussion above.)  However, a named function has no meaningful values to capture, making ''function'' more appropriate.
  
-==== Related RFCs ====+===== Related RFCs =====
  
 A number of other RFCs in active consideration would complement short functions.  They may or may not pass, but if they did then they would benefit from short functions without any further effort. A number of other RFCs in active consideration would complement short functions.  They may or may not pass, but if they did then they would benefit from short functions without any further effort.
  
-=== Piped functions ===+==== Piped functions ====
  
 The [[rfc:pipe-operator-v2|pipe operator]] |> is still pending in an RFC, but the feedback on it before was generally positive.  Short functions would allow a function to be easily defined as the composition of several other functions. The [[rfc:pipe-operator-v2|pipe operator]] |> is still pending in an RFC, but the feedback on it before was generally positive.  Short functions would allow a function to be easily defined as the composition of several other functions.
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 </code> </code>
  
-Which is a really nice way to build up a pipeline through composition.  (Modulo PHP's clumsy way of referencing functions by name, which is a separate matter being addressed elsewhere.)+Which is a really nice way to build up a pipeline through composition.  Modulo PHP's clumsy way of referencing functions by name, which is a separate matter that would be addressed by the [[rfc:partial_function_application|Partial Function Application]] RFC The three RFCs together would allow for this:
  
-=== clone-with ===+<code php> 
 +function doAThing(User $u) => $u 
 +    |> step1(?)  
 +    |> step2(?) 
 +    |> step3($val, ?)  
 +    |> step4(?, $var) 
 +
 +</code> 
 + 
 + 
 +==== clone-with ====
  
 Although no formal RFC has been proposed, Máté had discussed a ''clone with'' syntax ([[https://github.com/php/php-src/pull/6538|code]], [[https://externals.io/message/112624|thread]]) that would create a useful, single-expression clone-with-modification operation.  That is an excellent candidate for short-function "withX" methods. Although no formal RFC has been proposed, Máté had discussed a ''clone with'' syntax ([[https://github.com/php/php-src/pull/6538|code]], [[https://externals.io/message/112624|thread]]) that would create a useful, single-expression clone-with-modification operation.  That is an excellent candidate for short-function "withX" methods.
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 { {
     public function __construct(private int $x, private int $y) {}     public function __construct(private int $x, private int $y) {}
-     +
-    +
     public function getX(): int => $this->x;     public function getX(): int => $this->x;
     public function getY(): int => $this->y;     public function getY(): int => $this->y;
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 This is a simple up-or-down vote, requiring 2/3 approval to pass. This is a simple up-or-down vote, requiring 2/3 approval to pass.
  
-===== Patches and Tests =====+Voting started 2021-05-31 and closes 2021-06-14.
  
-[[https://github.com/php/php-src/pull/6221|Pull request with the code.]]+<doodle title="Include short-function syntax in PHP" auth="crell" voteType="single" closed="true"> 
 +   * Yes 
 +   * No 
 +</doodle>
  
-===== Implementation ===== +===== Patches and Tests =====
-After the project is implemented, this section should contain  +
-  - the version(s) it was merged into +
-  - a link to the git commit(s) +
-  - a link to the PHP manual entry for the feature +
-  - a link to the language specification section (if any)+
  
-===== References ===== +[[https://github.com/php/php-src/pull/6221|Pull request with the code.]]
-Links to external references, discussions or RFCs+
  
-===== Rejected Features ===== 
-Keep this updated with features that were discussed on the mail lists. 
rfc/short-functions.1616760890.txt.gz · Last modified: 2021/03/26 12:14 by nunomaduro