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--- rfc:alpanumeric_decrement [2014/01/28 00:45]
ajf Declined
+++ rfc:alpanumeric_decrement [2017/09/22 13:28]
@@ Line 1: / Line 1: @@
-====== PHP RFC: Alphanumeric Decrement ======
-  * Version: 1.0
-  * Date: 2013-12-16
-  * Author: Andrea Faulds <ajf@ajf.me>
-  * Status: Declined
-  * First Published at: http://wiki.php.net/rfc/alphanumeric_decrement
-===== Introduction =====
-This will add support for decrementing alphanumeric strings ("ab", for example) to complement the existing incrementing behaviour.
-===== Proposal =====
-At present, incrementing alphanumeric strings is supported. For example:
-  $x = "z";
-  $x++;
-  // $x is now "aa"
-However, decrementing alphanumeric strings is not:
-  $x = "z";
-  $x--;
-  // $x is still "z"
-Under this proposal, alphanumeric strings would be decrementable:
-  $x = "z";
-  $x--;
-  // $x is now "y"
-It would also handle the edge case of decrementing from "a", choosing to result in 0 (this may be subject to change):
-  $x = "a";
-  $x--;
-  // $x is now 0
-The patch at present additionally changes how empty strings are incremented. At present, it works as follows:
-  $x = "";
-  $x++;
-  // $x is now "1" (string)
-  $x = "";
-  $x--;
-  // $x is now -1 (int)
-With this patch, it is now consistent:
-  $x = "";
-  $x--;
-  // $x is now "-1" (string)
-===== Backward Incompatible Changes =====
-This might arguably be a BC break, as now decrementing for these strings would work, while existing code might assume that doesn't work. I doubt there is any code relying on that though, especially since "a"++ is a relatively obscure feature.
-===== Proposed PHP Version(s) =====
-Next PHP 5.x. Failing that, next PHP x.
-===== SAPIs Impacted =====
-None.
-===== Impact to Existing Extensions =====
-None.
-===== New Constants =====
-None.
-===== php.ini Defaults =====
-None.
-===== Open Issues =====
-How should decrementing "a" be handled? The patch and behaviour as proposed decrement to 0, however possibly not decrementing and emitting a warning might make more sense.
-===== Unaffected PHP Functionality =====
-Does not affect $x += 1 and $x -= 1, nor $x = $x + 1 and $x = $x - 1, as both of these do not support alphanumeric increment at present.
-===== Future Scope =====
-In future, alphanumeric increment being supported $x += 1 and $x = $x + 1 might be desirable, but that is not within the scope of this RFC.
-===== Vote =====
-Merge into PHP 5.6? (Will assume this requires 2/3 majority, due to new language feature)
-Voting started 2014-01-21 and ended 2014-01-28.
-<doodle title="Alphanumeric Decrement" auth="ajf" voteType="single" closed="true">
-   * Yes
-   * No
-</doodle>
-===== Patches and Tests =====
-https://github.com/php/php-src/pull/546
-Considered final patch, unless bugs are found.
-===== Implementation =====
-Not merged in at present.
-===== References =====
-Mailing list discussion: http://marc.info/?l=php-internals&m=138687859827708&w=1
-===== Rejected Features =====
-None as yet?

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