#49524 [Bgs]: Inequalities example in SWITCH documentation
ID: 49524
User updated by: matt at plasmacoustics dot com
Reported By: matt at plasmacoustics dot com
Status: Bogus
Bug Type: Documentation problem
Operating System: WinXP SP3
PHP Version: 5.3.0
New Comment:
Dan,
Here was the submission a fortnight ago:
http://bugs.php.net/bug.php?id=49679
as per your suggestion.
It was flagged 'Bogus'.
This week I debugged two clients scripts both suffering from this exact
logic error. Both developers had built on bad examples from SWITCH
documentation comments.
I brought attention to the widespread misunderstanding, resulting in
your snappy response.
I suggested a code example that will make this clear in future, which
was ignored.
If both you and fa don't wish to document the correct behaviour, please
just say so. Let us submitters and you developers try to read more
carefully and demonstrate some cohesion as a team.
Previous Comments:
------------------------------------------------------------------------
[2009-09-23 18:48:27] danbrown@php.net
I think that's a good idea, Matt. Would you please re-submit that as a
suggestion? Submitting it as a "Documentation problem," but with the
subject something along the lines of "Suggestion: Addition of Example
to
Switch Page" should suffice.
Also, feel free to supply an example you think would be of good use for
inclusion as an official example. Just be sure to test and re-test it,
just as we would ourselves. Some folks out there in userland make a
habit of simply copying and pasting code, thinking it will always work
as advertised (and be safe to run in the first place)! ;-P
Thanks for your efforts, Matt. We absolutely appreciate when folks
take
the time to help the community, such as you're continuing to do
yourself!
------------------------------------------------------------------------
[2009-09-23 18:27:06] matt at plasmacoustics dot com
Dan:
There is another example, see
http://au.php.net/manual/en/control-structures.switch.php#93342
If $totaltime is ZERO, a confusing semantic error would result.
Reliance on the arbitrary argument being interpreted as TRUE seems
widespread.
Why not add a SWITCH example covering INEQUALITIES to the
documentation?
------------------------------------------------------------------------
[2009-09-12 02:01:59] matt at plasmacoustics dot com
Thanks for pointing out the errors. You're right, there are many
mistakes in the submission, do feel free to delete it.
I do maintain though that the SWITCH argument would be best as TRUE to
guarantee the expected behaviour instead of relying on the type
conversion.
jonybd at yahoo dot com has a note that deals with inequalities. An
official example would be well received if you so wished. Cheers.
------------------------------------------------------------------------
[2009-09-11 15:41:57] danbrown@php.net
Three things to point out:
1.) You posted the bug from a completely different page than the one to
which you make reference.
2.) You grossly misquoted the code of which you complained.
3.) You didn't test it yourself, because - if you had - you'd see that
it works as advertised.
------------------------------------------------------------------------
[2009-09-10 16:33:48] matt at plasmacoustics dot com
Description:
------------
I feel the documentation on SWITCH might best include the appropriate
code for dealing with inequalities in a CASE, using switch(TRUE),
because people are posting User Notes with incorrect implementations.
Eg from: sedativchunk at gmail dot com
<?php
$rand=rand(1,50);
switch($randomizer) {
case ($randomizer <= 20):
$font_size = "11";
break;
}
?>
This isn't how switch() works! This will compare the value of
($randomizer) with the value of the inequality ($randomizer <= 20),
right?
Here is a better example of why it strikes me as dangerous:
<?php
$zero=0;
switch($zero) {
case($zero > 1):
print '0 > 1? No!';
break;
}
?>
The above code will go into the case because it sees:
$zero[FALSE] == ($zero > 1)[also FALSE], leading to great coder
confusion.
The ACTUAL desired behaviour should be implemented with the code:
<?php
$zero=0;
switch(TRUE) {
case($zero > 1):
print '0 > 1? No!';
break;
}
?>
Could we add an inequality example to the documentation and mend the
user-contributed note #88643?
Reproduce code:
---------------
---
From manual page: language.operators.comparison
---
------------------------------------------------------------------------
--
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