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Request #69486 Add support foir _toBoolean magic method
Submitted: 2015-04-20 08:02 UTC Modified: 2015-04-27 23:02 UTC
From: adrian at adecsys dot com Assigned:
Status: Open Package: Class/Object related
PHP Version: 5.4.40 OS: *
Private report: No CVE-ID: None
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From: adrian at adecsys dot com
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 [2015-04-20 08:02 UTC] adrian at adecsys dot com
Description:
------------
---
From manual page: http://www.php.net/language.oop5.magic
---

The inbuilt conversion of objects to Boolean, especially for expression evaluation, is poor and could be greatly improved.

I propose one of two mechanisms:

(a) Given the existing __toString() magic method, use this as an intermediate step in the conversion to a bool value, following the documented rules for string.

or 
(b) add support for an explicit __toBoolean magic method, which allows the implentation to take full control over the resulting type.

Thank you

Test script:
---------------
class NullObject {
  public function __toString() { return ""; }
  public function __toBoolean() { return false; }
  public function __call($name , $arguments) { return $this; }
}

$test = new NullObject();
echo $test ? "TRUE" : "FALSE" ;

// TRUE, but logically expect FALSE



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 [2015-04-20 08:49 UTC] requinix@php.net
-Package: PHP Language Specification +Package: Class/Object related
 [2015-04-27 23:02 UTC] cmb@php.net
-Operating System: CentOS/WinXP +Operating System: *
 [2015-04-27 23:02 UTC] cmb@php.net
Proposal A would constitute a BC break, though. Consider existing
code relying on boolean type juggling (or a cast) to test for
object existence, where the object has a __toString method
returning a "falsy" value (like in the given test script).

With regard to proposal B: how is int (or float) juggling, for
instance, supposed to work?

  (int) $obj->__toString()
  (int) $obj->__toBoolean()
  (int) $obj
 
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