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Date: Mon, 17 Dec 2007 12:45:42 +0300
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To: Jessie Hernandez <jrhernandez05@gmail.com>
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Subject: Re: [PHP-DEV] Re: Idea for namespace lookup resolution
From: dmitry@zend.com (Dmitry Stogov)

Hi Jessie,

The namespace may include several files and it may be extended with 
additional files in any moment. So having single 
__get_namespace_classes() function will require to update it every time 
you extend namespace.

Also such function will significantly slowdown access to internal 
classes. (It was the main reason why __autoload() was moved after check 
for internal class).

Thanks. Dmitry.

Jessie Hernandez wrote:
> Attached is the proof-of-concept patch. If the idea is met well, then 
> I'll keep working on it to add caching and, if there's interest, I'll 
> add *namespace imports*.
> 
> An example of how a class in a namespace that's named the same as an 
> internal class can be loaded:
> 
> autoload.php
> <?php
> function __autoload($className)
> {
>     include_once str_replace( '::', DIRECTORY_SEPARATOR, $className ) . 
> '.php';
> }
> 
> function __get_namespace_classes($namespaceName)
> {
>     return array( 'Exception' );
> }
> ?>
> 
> test.php
> <?php
> namespace ns;
> 
> include 'autoload.php';
> $ex = new Exception();
> var_dump( $ex ); // prints out ns:Exception instead of Exception
> ?>
> 
> 
> I ran a few tests on it and did not find any significant performance 
> hit. If possible, I'd like someone to try it out and see if they have 
> the same result.
> 
> As always, comments/suggestions on the patch are welcome.
> 
> 
> Regards,
> 
> Jessie Hernandez
> Zend Certified Engineer (http://zend.com/zce.php?c=ZEND006359&r=222727282)
> 
> 
> Jessie Hernandez wrote:
>> I just thought of something that might be a solution to the lookup 
>> rules that we currently have in the namespaces implementation. Whether 
>> it's good or not, I just wanted to throw it out there. Here goes:
>>
>> Support a user-defined function named __get_namespace_classes, which 
>> will be similar to __autoload. The signature of the function would be 
>> the following:
>>
>>
>> array __get_namespace_classes(string $namespaceName);
>>
>> Returns an array of names of classes that are under the specified 
>> namespace, or FALSE if the classes under the namespace could not be 
>> determined.
>>
>>
>> The above function would be used in the lookup rules as follows (using 
>> DateTime as an example):
>>
>> 1) Does the class DateTime exist in the current namespace?
>> 2) If not, and the function __get_namespace_classes exists, call 
>> __get_namespace_classes.
>> 3) If the string DateTime is returned in the array from 
>> __get_namespace_classes, then autoload that class.
>> 4) If the class is not in the resulting array, or if the result was 
>> FALSE, then look for an internal class DateTime.
>>
>>
>> With the above function, you can define classes inside your namespace 
>> that are named the same as internal classes without having to 
>> explicitly "use" them all over the place. You also solve the problem 
>> of namespace imports (sorry, use :-) ):
>>
>> <?php
>> use PEAR::Net::*;
>>
>> $a = new FTP();
>>
>> // The above "use" statement results in calling the
>> // __get_namespace_classes function and "using" each class in the
>> // resulting array internally. Meaning the above will be equivalent to
>> // this:
>> //
>> // use PEAR::Net::Curl;
>> // use PEAR::Net::DNS;
>> // use PEAR::Net::FTP;
>> // ...etc...
>> ?>
>>
>>
>> For the above function to work best, the PHP "dir" function, as an 
>> example, should be modified to have an additional "use_include_path" 
>> argument:
>>
>> object dir(string $directory [, bool $use_include_path])
>>
>>
>> By passing TRUE as the second argument, the directory will be searched 
>> for in the include path. The user can then do something like the 
>> following as an implementation of __get_namespace_classes (assuming 
>> the user organized it into class per file, as is common):
>>
>> <?php
>> function __get_namespace_classes($namespaceName)
>> {
>>     $classes = false;
>>     $nsDir = str_replace( '::', DIRECTORY_SEPARATOR, $namespaceName );
>>     $d = dir( $nsDir, true );
>>
>>     if( $d )
>>     {
>>         $classes = array();
>>
>>         while( ( $file = $d->read() ) !== false )
>>             $classes[] = str_replace( '.php', '', $file );
>>
>>         $d->close();
>>     }
>>
>>     return $classes;
>> }
>> ?>
>>
>>
>> Let me know what you think!
>>
>>
>>
>> Regards,
>>
>> Jessie
>