Re: NAN and INF cast to int

From: Date: Fri, 03 Jan 2014 01:51:36 +0000
Subject: Re: NAN and INF cast to int
References: 1 2  Groups: php.internals 
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On 02/01/2014 19:55, Yasuo Ohgaki wrote:

I've added this to the RFC as an issue.
https://wiki.php.net/rfc/comparison_inconsistency


The introduction on that RFC links to a rather confused bug report about min() and max() behaviour with mixed types. [1] The actual behaviour for comparisons between types is documented on the manual page for Comparison Operators [2], and is a largely separate issue to the behaviour of the actual conversions - it is not a question of how the values behave when converted, but which conversions are applied.

The current documentation for min() and max() is thoroughly unhelpful, implying special cases which don't exist, and missing behaviours that do. I submitted a patch on edit.php.net with revised examples and a clearer explanation and link to that page, but there seems to have been a glitch somewhere: the patches showed in the "Contributions are ready" reports for a while [3] but then seemingly disappeared without trace - I asked if anyone knew where they were, but nobody answered [4].

The non-commutativity of conversions does make this all very confusing (sorting arrays containing mixed types is actually unpredictable in some cases, and again the documentation is rather lacking), but is inevitable since such conversions may be "lossy" - e.g. (bool)42, (bool)43, and (bool)44 cannot possibly be distinct values. The only other option in many cases is simply to throw an error when such a comparison is attempted, and reject the entire computation.

Links:
[1] https://bugs.php.net/bug.php?id=53104
[2] http://php.net/manual/en/language.operators.comparison.php
[3] http://news.php.net/php.doc/969384748
[4] http://news.php.net/php.doc/969384775

Regards,

-- 
Rowan Collins
[IMSoP]

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