Bug #55416 [Com]: array_map() throws PHP warning if the callback throws an exception
Edit report at https://bugs.php.net/bug.php?id=55416&edit=1
ID: 55416
Comment by: harvey dot robin at gmail dot com
Reported by:roan dot kattouw at gmail dot com
Summary:array_map() throws PHP warning if the callback
throws an exception
Status: Open
Type: Bug
Package:Arrays related
Operating System: Ubuntu Natty
PHP Version:5.4.0alpha3
Block user comment: N
Private report: N
New Comment:
I've just come across this too and I'm really surprised at this inconsistent
behavior, for me the question isn't "what kind of situation needs throw a
exception in map function" but "why would the map function behave differently
to any other situation". If you change array_map to array_walk in the original
example then the exception propagates upward, as expected.
At the very least, I'd expect to see a note on the PHP manual page warning
users that exceptions work differently for the callback parameter to array_walk.
Previous Comments:
[2011-08-16 16:20:17] mah at everybody dot org
http://www.mediawiki.org/wiki/Special:Code/MediaWiki/94433 has Roan's actual
use case.
[2011-08-15 09:35:40] roan dot kattouw at gmail dot com
Basically what I'm doing is
implode("\n", array_map('readStyleFile', $files)
where $files is an array of file names, and readStyleFile() can throw an
exception if something is wrong (in this case it's if the file doesn't exist,
but other cases are imaginable). This exception then propagates up a few levels
and is caught and handled. Throwing an exception from inside the map callback
works just fine: it stops the callback, stops array_map(), propagates up to the
caller of array_map(), then works its way up the call stack like any other
exception. The only issue is that warning that won't go away.
[2011-08-15 08:54:02] larue...@php.net
I was wondering what kind of situation needs throw a exception in map function?
and why doing that? thanks
[2011-08-13 20:40:11] roan dot kattouw at gmail dot com
Something I forgot to mention in the original report:
Using @array_map(...) suppresses the warning. However, it also suppresses any
other notices or warnings that might happen in the callback. That's why I put
the $foo = $bar['baz']; bit in barf(): if you use @array_map, the "Undefined
variable" notice, which is legitimate, goes away as well.
More generally, @ is kind of a blunt instrument that often suppresses more than
you expect it to, masking mistakes.
[2011-08-13 20:32:50] roan dot kattouw at gmail dot com
The attached patch fixes this by not throwing the warning if EG(exception) is
not NULL. IMO the warning should be removed completely (because it's
superfluous, and I don't see offhand how it can be triggered other than by an
exception, but I don't know PHP core at all), but it's easy to tweak my patch
into doing that instead; this patch is just the minimal solution.
The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at
https://bugs.php.net/bug.php?id=55416
--
Edit this bug report at https://bugs.php.net/bug.php?id=55416&edit=1
Bug #55416 [Com]: array_map() throws PHP warning if the callback throws an exception
Edit report at https://bugs.php.net/bug.php?id=55416&edit=1
ID: 55416
Comment by: mah at everybody dot org
Reported by:roan dot kattouw at gmail dot com
Summary:array_map() throws PHP warning if the callback
throws an exception
Status: Open
Type: Bug
Package:Arrays related
Operating System: Ubuntu Natty
PHP Version:5.4.0alpha3
Block user comment: N
Private report: N
New Comment:
http://www.mediawiki.org/wiki/Special:Code/MediaWiki/94433 has Roan's actual
use case.
Previous Comments:
[2011-08-15 09:35:40] roan dot kattouw at gmail dot com
Basically what I'm doing is
implode("\n", array_map('readStyleFile', $files)
where $files is an array of file names, and readStyleFile() can throw an
exception if something is wrong (in this case it's if the file doesn't exist,
but other cases are imaginable). This exception then propagates up a few levels
and is caught and handled. Throwing an exception from inside the map callback
works just fine: it stops the callback, stops array_map(), propagates up to the
caller of array_map(), then works its way up the call stack like any other
exception. The only issue is that warning that won't go away.
[2011-08-15 08:54:02] larue...@php.net
I was wondering what kind of situation needs throw a exception in map function?
and why doing that? thanks
[2011-08-13 20:40:11] roan dot kattouw at gmail dot com
Something I forgot to mention in the original report:
Using @array_map(...) suppresses the warning. However, it also suppresses any
other notices or warnings that might happen in the callback. That's why I put
the $foo = $bar['baz']; bit in barf(): if you use @array_map, the "Undefined
variable" notice, which is legitimate, goes away as well.
More generally, @ is kind of a blunt instrument that often suppresses more than
you expect it to, masking mistakes.
[2011-08-13 20:32:50] roan dot kattouw at gmail dot com
The attached patch fixes this by not throwing the warning if EG(exception) is
not NULL. IMO the warning should be removed completely (because it's
superfluous, and I don't see offhand how it can be triggered other than by an
exception, but I don't know PHP core at all), but it's easy to tweak my patch
into doing that instead; this patch is just the minimal solution.
[2011-08-13 19:58:06] roan dot kattouw at gmail dot com
Description:
If you map a function on an array using array_map(), and that function (the
callback) then throws an exception, you get a PHP Warning saying "An error
occurred while invoking the map callback". I guess this is sort of reasonable
if an actual error occurred (even though that error would presumably have
reported itself already, so it's superfluous), but an exception isn't an actual
error unless the code that catches the exception decides it is.
This is annoying me because I'm squashing PHP warnings and notices in my code,
but I can't get rid of this warning. I have a legitimate use case for throwing
an exception from my map function, so I can either rewrite my code to not use
an exception there (which would be extremely awkward) or write a foreach
equivalent of the array_map() call (which would just be ridiculous; PHP
provides array_map() for a reason: so you can write one-liners instead of
repetitive foreach loops), or remove the IMHO misplaced warning in PHP.
I'll dig into the PHP source and see if I can come up with a patch.
Test script:
---
error_reporting(E_ALL);
function barf($i) {
$foo = $bar['baz'];
throw new Exception('barf');
}
$a = array(1, 2, 3);
try {
array_map('barf', $a);
} catch(Exception $e) {
echo $e;
}
Expected result:
Notice: Undefined variable: bar in /home/catrope/php-5.4.0alpha3/testcase.php
on line 3
exception 'Exception' with message 'barf' in
/home/catrope/php-5.4.0alpha3/testcase.php:3
Stack trace:
#0 [internal function]: barf(1)
#1 /home/catrope/php-5.4.0alpha3/testcase.php(6): array_map('barf', Array)
Actual result:
--
Notice: Undefined variable: bar in /home/catrope/php-5.4.0alpha3/testcase.php
on line 3
Warning: array_map(): An error occurred while invoking the map callback in
/home/catrope/php-5.4.0alpha3/testcase.php on line 6
exception 'Exception' with message 'barf' in
/home/catrope/php-5.4.0alpha3/testcase.php:3
Stack trace:
#0 [internal function]: barf(1)
#1 /home/catrope/php-5.4.0alpha3/testcase.php(6): array_map('barf', Array)
Bug #55416 [Com]: array_map() throws PHP warning if the callback throws an exception
Edit report at https://bugs.php.net/bug.php?id=55416&edit=1
ID: 55416
Comment by: roan dot kattouw at gmail dot com
Reported by:roan dot kattouw at gmail dot com
Summary:array_map() throws PHP warning if the callback
throws an exception
Status: Open
Type: Bug
Package:Arrays related
Operating System: Ubuntu Natty
PHP Version:5.4.0alpha3
Block user comment: N
Private report: N
New Comment:
The attached patch fixes this by not throwing the warning if EG(exception) is
not NULL. IMO the warning should be removed completely (because it's
superfluous, and I don't see offhand how it can be triggered other than by an
exception, but I don't know PHP core at all), but it's easy to tweak my patch
into doing that instead; this patch is just the minimal solution.
Previous Comments:
[2011-08-13 19:58:06] roan dot kattouw at gmail dot com
Description:
If you map a function on an array using array_map(), and that function (the
callback) then throws an exception, you get a PHP Warning saying "An error
occurred while invoking the map callback". I guess this is sort of reasonable
if an actual error occurred (even though that error would presumably have
reported itself already, so it's superfluous), but an exception isn't an actual
error unless the code that catches the exception decides it is.
This is annoying me because I'm squashing PHP warnings and notices in my code,
but I can't get rid of this warning. I have a legitimate use case for throwing
an exception from my map function, so I can either rewrite my code to not use
an exception there (which would be extremely awkward) or write a foreach
equivalent of the array_map() call (which would just be ridiculous; PHP
provides array_map() for a reason: so you can write one-liners instead of
repetitive foreach loops), or remove the IMHO misplaced warning in PHP.
I'll dig into the PHP source and see if I can come up with a patch.
Test script:
---
error_reporting(E_ALL);
function barf($i) {
$foo = $bar['baz'];
throw new Exception('barf');
}
$a = array(1, 2, 3);
try {
array_map('barf', $a);
} catch(Exception $e) {
echo $e;
}
Expected result:
Notice: Undefined variable: bar in /home/catrope/php-5.4.0alpha3/testcase.php
on line 3
exception 'Exception' with message 'barf' in
/home/catrope/php-5.4.0alpha3/testcase.php:3
Stack trace:
#0 [internal function]: barf(1)
#1 /home/catrope/php-5.4.0alpha3/testcase.php(6): array_map('barf', Array)
Actual result:
--
Notice: Undefined variable: bar in /home/catrope/php-5.4.0alpha3/testcase.php
on line 3
Warning: array_map(): An error occurred while invoking the map callback in
/home/catrope/php-5.4.0alpha3/testcase.php on line 6
exception 'Exception' with message 'barf' in
/home/catrope/php-5.4.0alpha3/testcase.php:3
Stack trace:
#0 [internal function]: barf(1)
#1 /home/catrope/php-5.4.0alpha3/testcase.php(6): array_map('barf', Array)
--
Edit this bug report at https://bugs.php.net/bug.php?id=55416&edit=1
