Including once

[Xu Wei Jie]

Hi all,

 

How do I include once a library?

I mean not in the fashion of using include_once(). But implementing something that is similar to it

 

If the library is ever loaded, I would escape from loading it again.

 

Will this code work if I put in the beginning of the library code?

 

library.php
<?php
if (isset($pp_loaded__)) return 1;

$pp_loaded__ = true;

//load library functions here
?>

[Daniel0]

Just store a list of included libraries and check against it each time you are going to include something. If it already exists in the list then abort.

[Xu Wei Jie]

Actually i want to achieve something like when the user includes twice or more times the library itself, PHP won't prompt warnings like re declared functions and etc.

 

//test.php
<?php
include("library.php")
include("library.php")
include("library.php")
include("library.php")
?>

 

Using a list to keep track may be a good idea but if multiple files are involved, the list may be hard to pass from one file to another. It gets complicated.

 

Consider this example

 

//a.php
<?php 
include("library.php");
include("b.php");
?>

//b.php
<?php 
include("library.php");
?>

 

Thus I want to find a way to return out of the included library if it was ever loaded before.

[Daniel0]

That's what you use include_once for...

[Xu Wei Jie]

I want to simulate the same behavior without using include_once. I wish to design the library such that the programmer need not be mindful whether to use include or include_once. He/She just need to include the library using whichever include he/she prefer and the library will detect for itself whether it has been loaded or not loaded before.

[Daniel0]

Whatever you come up with will most definitely be less efficient than using the built-in include_once()/require_once() functionality because those are written in C. Just always use _once and you won't have to think about it.

[Mark Baker]

If you really have to rewrite PHP, why not take a look at the APD extension

 

override_function('include', '$fileName', 'include_once($fileName)' );

[Xu Wei Jie]

Anyway, I tried

 

if(isset($loaded)) return

else $loaded="set";

 

This code does not work though because $loaded seems to be a new instance every time the library is included.

 

Another way is to add another level of include_once inside the library =)

 

library.php

<?php

include_once("library_functions.php");

?>