Bug #60694 [Opn]: print() results in bad logic
Edit report at https://bugs.php.net/bug.php?id=60694&edit=1
ID: 60694
User updated by: MarkAndrewSlade at gmail dot com
Reported by: MarkAndrewSlade at gmail dot com
Summary: print() results in bad logic
Status: Open
Type: Bug
Package: Scripting Engine problem
Operating System: CentOS release 5.4 (Final)
PHP Version: 5.3.8
Block user comment: N
Private report: N
New Comment:
Oh, I see what happened. I agree with your recommendation. The documentation
says they are "not required" (implying optional), and they are used in the
actual example. I normally use echo, and without parens, so I just kinda
randomly came across this.
I'm not sure if you were saying the parser's interpretation was invalid or mine,
but in case the latter and this is considered correct parsing, the documentation
should be updated to reflect that it's "print <string>", without parens.
Developers can deduce for themselves that "print ('foo')" is allowed, but the
semantics will be clearer.
Previous Comments:
------------------------------------------------------------------------
[2012-01-10 10:24:08] phpmpan at mpan dot pl
Invalid interpretation of the code caused by misleading parenthenses.
1. false && print ('')
-> false && (print (''))
-> false && 1
-> false
2. print('') && false
-> (print (('') && false))
-> (print false)
-> 1
-> true
3. print('') && false && false
-> (print ((('') && false) && false))
-> (print false)
-> 1
-> true
4. (print('') && false) && true
-> ( print (('') && false) ) && true
-> (print false) && true
-> 1 && true
-> true
5. (print('') && false) && false
-> (print (('') && false) && false
-> (print false) && false
-> 1 && false
-> false
I believe that documentation for all language constructs (echo, include,
print, ...) should explicitly discourage use of parenthenses around arguments.
They're very misleading.
------------------------------------------------------------------------
[2012-01-10 02:26:21] MarkAndrewSlade at gmail dot com
Description:
------------
Unlike echo, the print construct is allowed inside logic clauses. If it is
reached (not short-circuited), it will cause the rest of that clause to be true.
Tested with 5.3.8 and PHP 5.3.9RC5-dev, both with default configure.
Test script:
---------------
<?php
echo (false && print('')) ? "Fail\n" : "Pass\n";
echo (print('') && false) ? "Fail\n" : "Pass\n";
echo (print('') && false && false) ? "Fail\n" :
"Pass\n";
echo ((print('') && false) && true) ? "Fail\n" :
"Pass\n";
echo ((print('') && false) && false) ? "Fail\n" :
"Pass\n";
?>
Expected result:
----------------
The word "Pass" five times.
Actual result:
--------------
The middle three fail. The first and last pass, and are included to demonstrate
the limits of the bug.
------------------------------------------------------------------------
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