Understanding error masking in error handling...

> Hey all :)
>
> I was wondering about the $error_types (I particularly notice the 's' suffix
> when reading the manual) parameter for 'set_error_handler()':
>
> Can be used to mask the triggering of the error_handler function just like
> the error_reporting ini setting controls which errors are shown. Without
> this mask set the error_handler will be called for every error regardless
> to the setting of the error_reporting setting.
>
> And, in my php.ini I have,
> error_reporting = E_ALL & ~E_NOTICE
>
> Which - I think - means something like "E_ALL and less severe AND NOT
> E_NOTICE in particular".
>
> This may be read wrong, but in essence, what I assume is possible is to
> create a mask that very particularly lets you define which errors to handle
> with your custom error handler, and which not to. But I cannot find any
> documentation telling me how this works.
>
> I would like, rather than having to do something like -
>
> if (DEVELOPMENT_MODE && in_array($error_level, array(E_WARNING,
> E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE, E_RECOVERABLE_ERROR,
> E_DEPRECATED, E_USER_DEPRECATED)) log_to_screen($message);
>
> - on every error/notice/whatever comes by my custom error handler, to be
> able to specify a mask that essentially does the same only in my
> set_error_handler call.
>
> This may seem superfluous, but what I'm creating right now are core services
> that should service upwards of hundreds of frontends simultaneously, so
> whatever small performance gain I can achieve here and there may lead to a
> tremendous effect overall.
>
> Can anyone help me with understanding this masking business? Or I have I
> misunderstood the concept entirely? :)
>
> Thanks in advance,
> Daniel :)

> Daniel Smedegaard Buus schreef:
>> Hey all :)
>>
>> I was wondering about the $error_types (I particularly notice the 's'
>> suffix when reading the manual) parameter for 'set_error_handler()':
>>
>> Can be used to mask the triggering of the error_handler function just
>> like the error_reporting ini setting controls which errors are shown.
>> Without
>> this mask set the error_handler will be called for every error
>> regardless to the setting of the error_reporting setting.
>>
>> And, in my php.ini I have,
>> error_reporting = E_ALL & ~E_NOTICE
>>
>> Which - I think - means something like "E_ALL and less severe AND NOT
>> E_NOTICE in particular".
>>
>> This may be read wrong, but in essence, what I assume is possible is to
>> create a mask that very particularly lets you define which errors to
>> handle with your custom error handler, and which not to. But I cannot
>> find any documentation telling me how this works.
>>
>> I would like, rather than having to do something like -
>>
>> if (DEVELOPMENT_MODE && in_array($error_level, array(E_WARNING,
>> E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE, E_RECOVERABLE_ERROR,
>> E_DEPRECATED, E_USER_DEPRECATED)) log_to_screen($message);
>>
>> - on every error/notice/whatever comes by my custom error handler, to be
>> able to specify a mask that essentially does the same only in my
>> set_error_handler call.
>>
>> This may seem superfluous, but what I'm creating right now are core
>> services that should service upwards of hundreds of frontends
>> simultaneously, so whatever small performance gain I can achieve here and
>> there may lead to a tremendous effect overall.
>>
>> Can anyone help me with understanding this masking business? Or I have I
>> misunderstood the concept entirely? :)
>>
>> Thanks in advance,
>> Daniel :)
>
> Hi Daniel,
>
> I think you need to reread the manual:
> http://nl3.php.net/manual/en/function.set-error-handler.php
>
> [quote]
> It is important to remember that the standard PHP error handler is
> completely bypassed. error_reporting() settings will have no effect and
> your error handler will be called regardless - however you are still
> able to read the current value of error_reporting and act appropriately.
> Of particular note is that this value will be 0 if the statement that
> caused the error was prepended by the @ error-control operator.
> [/quote]
>

> So your custom errorhandler is called ALWAYS regardless the settings you
> put into error_reporting() (or via php.ini).
>
> Your errorhandler must deal with this error then.
> The errorhandler is called with a bunch of parameters, the first being
> the errornumber as listed here:
> http://nl3.php.net/manual/en/function.error-reporting.php
>
> So I am unsure why you care about the 'masking business', since it is of
> no concern to you (unless I completely misinterpret your posting).
>
> The passed errornumber can only be 1 of the errors listed (You cannot
> have 2 errors at the same time).
>
> Also, if you write your own handler, be sure you check for
> errorsupression.
>
> Here is the first peice of code of an errorhandler I use often:
>
> function errorHandler($number, $string, $file, $line, $context) {
> // If the user uses errorsurperrsion with @, we need to forgive this
> error!
> if (error_reporting() == 0){
> // The error was surpressed, return without futher interference.
> return;
> }
> // rest of the errorhandler
>

> }
>
> Good luck,
>
> Regards,
> Erwin Moller
>

>May I ask what the AND operator does?

>And the ~ in front of a constant, is that only for the php.ini
>setting, or is that also valid in php, and if so, what does it mean?

> On Tue, 11 Nov 2008 08:45:36 +0100, Daniel Smedegaard Buus
>
> [snip explanation of bit fields]
>
>>May I ask what the AND operator does?
>
> Assuming that you mean the "&" operator, it keeps only the bits that
> are set in both variables. E.g. 2 & 3 = 2
>
> 00000010 // 2 base 2
> 00000011 // 3 base 2
> --------
> 00000010 // keeps only the bit in the two's place
> // because it's the only one set in both
>
>
>>And the ~ in front of a constant, is that only for the php.ini
>>setting, or is that also valid in php, and if so, what does it mean?
>
> It's the complement operator, which inverts the bits. E.g. if 2 is
> 00000010 then it's complement is 11111101. It's useful for removing a
> bit from a bitfield. Saying E_ALL & ~ E_NOTICE is a way of saying
> "everything except for notices".