Everything

php

Home » Project » Newsgroups » php.internals » output buffering callback limitation »

output buffering callback limitation

php.internals

Okin Okin

22 years ago

Hi,

I'm having trouble with output buffering limitation
and the output_callback function of ob_start.

look at this script :

<?php

function ob_perso_handler($buffer)
{
ob_start();
echo 'foo';
$buffer .= ob_get_contents();
ob_end_clean();

return $buffer;
}

ob_start('ob_perso_handler');

echo 'Hello World !';

?>

it outputs : "Fatal error: ob_start(): Cannot use
output buffering in output buffering display handlers"


Why then ? It would be a killer  feature for my next
killer appz !

I've tried also :

<?php

function ob_perso_handler1($buffer)
{
return $buffer . 'f1';
}

function ob_perso_handler2($buffer)
{
?>
foo
<?

return $buffer . 'f2';
}

ob_start('ob_perso_handler1');
ob_start('ob_perso_handler2');

echo 'Hello World !';

?>

but were does "foo" go ?


any idea on that ? maybe some source change to PHP to
permit one or the other solution ?

I'm new to this mailing list, please redirect me to
the correct one if I'm wrong here. My thought was it
was a developper problem, since change to the source
has to be done to enable such this feature ...

Many thank's for any help !

Nikos






Yahoo! Mail : votre e-mail personnel et gratuit qui vous suit partout !
Créez votre Yahoo! Mail sur http://fr.benefits.yahoo.com/

Dialoguez en direct avec vos amis grâce à Yahoo! Messenger !Téléchargez Yahoo! Messenger sur http://fr.messenger.yahoo.com

Taco van den Broek

22 years ago

Okin okin wrote:

> Hi,
>
> I'm having trouble with output buffering limitation
> and the output_callback function of ob_start.
>
> look at this script :
>
> <?php
>
> function ob_perso_handler($buffer)
> {
> 	ob_start();
> 	echo 'foo';
> 	$buffer .= ob_get_contents();
> 	ob_end_clean();
>
> 	return $buffer;
> }
>
> ob_start('ob_perso_handler');
>
> echo 'Hello World !';
>
> ?>
>
> it outputs : "Fatal error: ob_start(): Cannot use
> output buffering in output buffering display handlers"
>
>
> Why then ? It would be a killer  feature for my next
> killer appz !
>
> I've tried also :
>
> <?php
>
> function ob_perso_handler1($buffer)
> {
> 	return $buffer . 'f1';
> }
>
> function ob_perso_handler2($buffer)
> {
> 	?>
> 	foo
> 	<?
>
> 	return $buffer . 'f2';
> }
>
> ob_start('ob_perso_handler1');
> ob_start('ob_perso_handler2');
>
> echo 'Hello World !';
>
> ?>
>
> but were does "foo" go ?
>
>
> any idea on that ? maybe some source change to PHP to
> permit one or the other solution ?
>
> I'm new to this mailing list, please redirect me to
> the correct one if I'm wrong here. My thought was it
> was a developper problem, since change to the source
> has to be done to enable such this feature ...
>
> Many thank's for any help !
>
> Nikos
>
>
>
>
>
>
> Yahoo! Mail : votre e-mail personnel et gratuit qui vous suit partout !
> Créez votre Yahoo! Mail sur http://fr.benefits.yahoo.com/
>
> Dialoguez en direct avec vos amis grâce à Yahoo! Messenger !Téléchargez Yahoo! Messenger sur http://fr.messenger.yahoo.com

I don't really understand your problem, it seams to me you want to add
output to the buffer in the output handler!?

Why not just:
<?php
function myObHandler($buffer)
{
$buffer .= 'foo';
return $buffer;
}
ob_start('myObHandler');
?>

-Taco

Okin Okin

22 years ago

One last note on this :

the limitation I'm talking about is annoying in two cases for me :
- I can't use "print_r($var, true)" inside an ob_handler, because print_r uses ob_start internally. And I need this to append some debug info to my buffer. The workaround for this is to make my own print_r...

- In some cases, I would like to send an email from an ob_handler. But I make my emails with some logic/presentation separation. And most if not all template systems use ob_start to fetch their output into a $variable. The workaround here is to register_shutdown_function the mail-sending function inside the ob_handler.

As you can see, I've two real problems, and a real solution (by PHP source mods) could be far better than two workarounds isn't it ?

One would allow ob_start to be called inside an ob_handler, and the error message would be printed only if output buffering is always on at the end of this ob_handler, it would be perfect !

Please consider this idea, and thank you for your patience.

Nikos

Taco van den Broek <taco@procurios.nl> wrote:

Okin okin wrote:

> I'm having trouble with output buffering limitation
> and the output_callback function of ob_start.
>
> look at this script :
>
> function ob_perso_handler($buffer)
> {
> ob_start();
> echo 'foo';
> $buffer .= ob_get_contents();
> ob_end_clean();
>
> return $buffer;
> }
>
> ob_start('ob_perso_handler');
>
> echo 'Hello World !';
>
> ?>
>
> it outputs : "Fatal error: ob_start(): Cannot use
> output buffering in output buffering display handlers"
>

I don't really understand your problem, it seams to me you want to add
output to the buffer in the output handler!?

Why not just:

<?php
function myObHandler($buffer)
{
$buffer .= 'foo';
return $buffer;
}
ob_start('myObHandler');
?>


---------------------------------
Yahoo! Mail : votre e-mail personnel et gratuit qui vous suit partout !
Créez votre Yahoo! Mail

Dialoguez en direct avec vos amis grâce à Yahoo! Messenger !

Andre Cerqueira

22 years ago

I think an ob_handler should be designed to handle output.
Not create (output), nor send emails.
I think the workaround is the other way around hehe
It's the way you want it to work that is a workaround, since there is
probably a better way to do it.


-I agree, print_r($var, true) should work but doesn't.
You could print_r() before or after ob_handler being called (upon script
end or ob_end_flush, or something like that)

-I think you could still send the email from the ob_handler (though i
think it's ugly) and keep the separation if you read the template file
and handle it instead of including directly after a ob_start() (that's
what you're doing, right?)
Or you could send the email out of the ob_handler

> One would allow ob_start to be called inside an ob_handler, and the
>error message would be printed only if output buffering is always on

at >the end of this ob_handler, it would be perfect !

Not sure if i undertood you. Are you trying to emit errors during
ob_handler execution and prevent them from being output using ob_start()?
You could use error_reporting()+error_log()[+trigger_error()] or something?

Okin okin wrote:

Okin Okin

22 years ago

>Not sure if i undertood you. Are you trying to emit
>errors during
>ob_handler execution and prevent them from being
>output using ob_start()?
>You could use

error_reporting()+error_log()[+trigger_error()] or
something?

Nop, I'm considering this :

<?php
function ob_perso_handler($buffer) {
ob_start();
echo 'foo';
return $buffer . ob_get_clean();
}

ob_start('ob_perso_handler');

echo 'Hello World !';
?>

this code produces "Fatal error: ob_start(): Cannot
use output [...]"

the idea is that the above code don't makes error
anymore, but this one yes

<?php
function ob_perso_handler($buffer) {
ob_start();
echo 'foo';
return $buffer;
}

ob_start('ob_perso_handler');

echo 'Hello World !';
?>

with an error message like this one :
"Fatal error: each output buffer started inside an
ob_handler must be destroyed before the end of this
ob_handler"

>Andre Cerqueira <accerqueira@superig.com.br> wrote: I

think an ob_handler should be designed to handle

>output.
>Not create (output), nor send emails.
>I think the workaround is the other way around hehe
>It's the way you want it to work that is a
>workaround, since there is
>probably a better way to do it.
>
>
>-I agree, print_r($var, true) should work but

doesn't.

>You could print_r() before or after ob_handler being
>called (upon script
>end or ob_end_flush, or something like that)

>-I think you could still send the email from the
>ob_handler (though i
>think it's ugly) and keep the separation if you read
>the template file
>and handle it instead of including directly after a
>ob_start() (that's
>what you're doing, right?)
>Or you could send the email out of the ob_handler
>
>
>> One would allow ob_start to be called inside an
>ob_handler, and the
>>error message would be printed only if output
>>buffering is always on
>>at the end of this ob_handler, it would be perfect !
>
>Not sure if i undertood you. Are you trying to emit
>errors during
>ob_handler execution and prevent them from being
>output using ob_start()?
>You could use

error_reporting()+error_log()[+trigger_error()] or
something?

>
>
>
>Okin okin wrote:
> One last note on this :
>
> the limitation I'm talking about is annoying in two

cases for me :

> - I can't use "print_r($var, true)" inside an

ob_handler, because print_r uses ob_start internally.
And I need this to append some debug info to my
buffer. The workaround for this is to make my own
print_r...

>
> - In some cases, I would like to send an email from

an ob_handler. But I make my emails with some
logic/presentation separation. And most if not all
template systems use ob_start to fetch their output
into a $variable. The workaround here is to
register_shutdown_function the mail-sending function
inside the ob_handler.

>
>
> Okin okin wrote:
>
>>I'm having trouble with output buffering limitation
>>and the output_callback function of ob_start.
>>
>>look at this script :
>>
>>function ob_perso_handler($buffer)
>>{
>>ob_start();
>>echo 'foo';
>>$buffer .= ob_get_contents();
>>ob_end_clean();
>>
>>return $buffer;
>>}
>>
>>ob_start('ob_perso_handler');
>>
>>echo 'Hello World !';
>>
>>?>
>>
>>it outputs : "Fatal error: ob_start(): Cannot use
>>output buffering in output buffering display

handlers"

Yahoo! Mail : votre e-mail personnel et gratuit qui vous suit partout !
Créez votre Yahoo! Mail sur http://fr.benefits.yahoo.com/

Dialoguez en direct avec vos amis grâce à Yahoo! Messenger !Téléchargez Yahoo! Messenger sur http://fr.messenger.yahoo.com

Andre Cerqueira

22 years ago

maybe php.general would be more appropriate

im not a developer, but i think this "feature" doesnt make sense hehe
i think ob display handlers are not supposed to output things directly,
they just return them to the function that will output it

at your first snip, you could/should do:

<?php
function ob_perso_handler($buffer)
{
$buffer = 'foo'. $buffer; //you already received output data
return $buffer;
}
ob_start('ob_perso_handler');
echo 'Hello World !';
?>

at the second:

<?php
function ob_perso_handler1($buffer)
{
return $buffer .'f1';
}

function ob_perso_handler2($buffer)
{
return 'foo'. $buffer .'f2';
}

ob_start('ob_perso_handler1');
ob_start('ob_perso_handler2');

echo 'Hello World !';
?>


good luck on the killer appz



Okin okin wrote: