including files

hi everyone

I've read that require_once is really slow. However, I'm not quite
sure *why* it is slow.. surely it is setting a variable in memory
somewhere, and everytime it wishes to include a file, it checks
whether that variable is set?! This to me doesn't seem like an
expensive operation!

In the case that require_once is prohibitively slow, are there any
other tactics in ensuring that files only get included once? PHPBB
uses a tactic where their include files don't actually pull in any
dependent files; they depend on whatever is including them to have
included the relevant files. I don't really like this option as it
doesn't explicitly state the dependencies an include file may have.

I was thinking of putting in C++ style include guards, but I'm
thinking this is how PHP would implement the require_once function!

Thanks

Taras

Taras_96 schreef:
> hi everyone
>
> I've read that require_once is really slow. However, I'm not quite
> sure *why* it is slow.. surely it is setting a variable in memory
> somewhere, and everytime it wishes to include a file, it checks
> whether that variable is set?! This to me doesn't seem like an
> expensive operation!

It is not slow.
Who told you that nonsense?
I use it all the time in all my sites without ever noticing any
perceivable slowdown.

Are you actually having performanceproblem because of including_once a file?

Of course, when the included file is huge, it takes PHP more time to
process it, but the same goes for all PHP files.

>
> In the case that require_once is prohibitively slow, are there any
> other tactics in ensuring that files only get included once? PHPBB
> uses a tactic where their include files don't actually pull in any
> dependent files; they depend on whatever is including them to have
> included the relevant files. I don't really like this option as it
> doesn't explicitly state the dependencies an include file may have.

Don't get into that mess.
Simply use include_once() and you will NOT run into any problems.

>
> I was thinking of putting in C++ style include guards, but I'm
> thinking this is how PHP would implement the require_once function!

Maybe it does, not sure.

>
> Thanks
>
> Taras

Don't fix it when it ain't broke.
Don't believe anything somebody wrote on the net.

You can simply benchmark the include_once() yourself easily with
microtime() and you'll probably find you don't have a problem.

Regards,
Erwin Moller

Hi there Erwin,

As you guessed, I'm mostly going off what people have written on the
web, such as http://uk2.php.net/manual/en/functio...once.php#62838.
I'm just starting out at the beginning of my project, so I'm trying to
establish the best file structure to use. The best way is to use
require_once, so that you can see what dependencies a library class
has (on other files/classes). Obviously if you are using require or
include, then you can't do this as it runs the great risk of trying to
include a file twice.

The fact that the phpBB software (which I assume, maybe incorrectly,
was written by people that know their PHP) goes to some lengths to
avoid the require_once construct implies that maybe there is a shred
of truth to require_once being slow.

There are no performance problems yet, but if our library code depends
on this construct, and later on we write some pages that experience a
very heavy load and are slow because of our use of require_once, then
we'd be forced to change the entire structure of our library, which is
a very very bad thing ;)

Taras

On Jul 15, 6:28*am, Taras_96 <taras...@gmail.com> wrote:
> I've read that require_once is really slow.

Really slow? No. It's a tiny bit slower than require(). Testing with
Apache ab, you'll notice a small reduction in requests/sec.

> other tactics in ensuring that files only get included once?

Follow the one-class-per-file and PEAR directory layout conventions.
Then you can rely on autoloading, or using something like this (in a
utility class):

// e.g.: loadClass('Foo_Bar_Crunch')
function loadClass($class_)
{
if (class_exists($class_, false) || interface_exists($class_,
false)) {
return;
}
require str_replace('_', DIRECTORY_SEPARATOR, $class_) . '.php';
}

Keep in mind the performance of require_once vs. autoload and the
function above may depend on your environment; it may not be worth the
hassle to avoid it.

Steve