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Posted by Oli Filth on 05/29/06 03:40
Norman Peelman said the following on 29/05/2006 00:05:
> "Chung Leong" <chernyshevsky@hotmail.com> wrote in message
> news:1148841404.688262.297960@i40g2000cwc.googlegroups.com...
>> Norman Peelman wrote:
>>> The bottom line is this... precedence can only 'guess' so much as to
> what
>>> you the programmer wants and it normally does a great job. But when you
>>> start mixing two different functions ('.' and '+') it has to make
>>> assumptions, and those assumptions are to work on what is immediately
> known
>>> and that is what is to the immediate left and right:
>> I'm sorry but you're missing the entire point of the discussion. The
>> point is that the ambiguity is illogical and should not exist. To use
>> your terminology, apples are apples, oranges are oranges. Putting them
>> all in one bin and then guess at what you've got is stupid.
>>
>
> So, what would you want to happen? Should the parser go through each
> entire string looking for math equations first then string everything
> together after.
Who has suggested anything of the sort?
> The bottom line is that '.' and '+' are/were not really meant to be used at
> the same time as one works with strings and one works with mathematics.
Says who?
> So normally there would be no ambiguity.
There's no ambiguity; the behaviour is well-defined. However, there
*is* unintuitive behaviour.
> If you want:
>
> $a = 'If you multiply ' + 2 + 5 + 3 + ' by ' + 2 * 5 + ' you get ' + 10 *
> 10;
>
> then you're asking too much of one operator let alone the parser.
Assuming you mean "overload {+} to do both string concatenation and
addition", then you may well be right, it probably wouldn't be possible
to come up with a sensible precedence scheme so that the above example
gave the same result as:
$a = 'If you multiply ' . (2 + 5 + 3) . ' by ' . (2 * 5) . ' you get ' .
(10 * 10);
However, we're not talking about operator overloading. What we're
talking about is the operator precedence in PHP being unintuitive. If
there were an "intuitive" operator precedence (with {.} lower than
{+,-}), then the code below would give the same result:
$a = 'If you multiply ' . 2 + 5 + 3 . ' by ' . 2 * 5 . ' you get ' . 10
* 10;
--
Oli
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