[PHP-DOC] #17386 [Opn]: Associativity of assignment operators listed wrongly From: john <email protected>
Date: 11/28/02

 ID: 17386
 Updated by: john <email protected>
 Reported By: m.ford <email protected>
 Status: Open
 Bug Type: Documentation problem
 PHP Version: 4.1.2
 Assigned To: john
 New Comment:

I'll make the change for the associtivity from left to right, but I
don't know if I should just make a note of the example regarding
precedence rules.

Anyone know if its intended behavior, or should this have thrown a
parse error?

John

Previous Comments:
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[2002-05-23 09:34:04] m.ford <email protected>

The operators page at /manual/en/language.operators.php lists the the
assignment operators (=, +=, etc.) as being left associative, but they
must logically be right associative. Left associativity would mean that
this:

    $a = $b = 0;

was interpreted as:

    ($a = $b) =0;

which is clearly nonsensical. Indeed a quick test shows that:

    $d = $c += $a += $b += 4;

is interpreted as:

    $d = ($c += ($a += ($b += 4)));

which looks like right associativity to me!

(Actually, a little further testing suggests that the assignment
operators need some special annotations, as they don't appear to
strictly obey their stated precedence level. For example, the
statement:

    $x = $z + $y = 543;

if interpreted strictly according to the precedence rules should be
equivalent to:

    $x = ($z + $y) = 543;

which would be a parse error, but in fact is interpreted as:

    $x = $z + ($y = 543);

which may be the "obvious" intention, but had me WTF-ing for a while!!)

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