I want to use the phpmailer library. If I install the Debian or Ubuntu package it will be at

/usr/share/php/libphp-phpmailer/class.phpmailer.php
/usr/share/php/libphp-phpmailer/class.pop3.php
/usr/share/php/libphp-phpmailer/class.smtp.php

Why do I need to put another copy at another place for drupal?
I use an account on a shared computer for drupal website. /usr/share/php is on a local disk and my account for drupal on NFS network shared disk, this makes a performance difference. They are hundreds of copies of drupal on theses server, so the operating system would need to put all libraries hundred of time in cache : those files cannot stay in cache for a long time. If I would use /usr/share/php/libphp-phpmailer/class.phpmailer.php and all other websites would do the same, it would be much more easy for the operating system to use a copy in cache, it would be faster and reduce server load... and for people installing drupal that would be just a lot easier because they would not need any more to upload this library to the server, the library module would just find it!

Comments

Version:7.x-2.0» 7.x-2.x-dev

If I understand this correctly (I might not, please correct me in that case), this is similar to #1117656: Add support for PEAR modules in that both issues are about loading libraries (PHP files in this case) from the PHP include path. That issue has been open for a while, we haven't yet figured out how to implement that cleanly in 7.x.-2.x but hope to solve this, among other things, in the upcoming 8.x-3.x branch. Marking against 7.x-2.x for now, because this is a concrete feature request and 8.x-3.x is mostly vaporware for now.

I am very happy to hear about it! Thanks very much. PEAR is a first step for sure. Other php and javascript libraries may also benefit from this improvement at some point, like stated in http://drupal.org/node/1117656#comment-4503804

I've now made a Debian package of the Libraries API, this helps address the problem:

http://danielpocock.com/drupal-on-debian-libraries-api

Very interesting!