function get_rev() {
	return (int)substr(substr('$Rev: 168 $', 6), 0, -2);
}

And add the Revision keyword to the properties of the file

svn propset svn:keywords Revision your_file.php

"$Rev: 168 $" will then automatically be updated on every commit.

In this case I have a system with a lot of users, each of which is mapped to a group. The groups are defined as a tree structure, but because of the roles of the system, the leaf node can never be more than three nodes away from the root. I need to show a list of, say all users not logged in the last 2 months, and the list should show in which groups the users is located.

I could find all users, get the group id from each users and with a recursive function in the application, find the parent group id of the group, get this group from the database, find the parent group id of the group, get this group from the database..... This would require a lot of database activity. It is also possible to make nested sets or stored procedures, but if the depth of the three is relative low (and known), I believe the below is simpler.

The table of groups is defined as:

CREATE TABLE `groups` (
	`gid` INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
	`pgid` INT NOT NULL ,
	`title` VARCHAR( 100 ) NOT NULL 
) ENGINE = MYISAM ;

With these groups:

mysql> select * from groups;
+-----+------+---------+
| gid | pgid | title   |
+-----+------+---------+
|   1 |    0 | Level 1 |
|   2 |    1 | Level 2 |
|   3 |    2 | Level 3 |
|   4 |    3 | Level 4 |
|   5 |    4 | Level 5 |
+-----+------+---------+
5 rows in set (0.00 sec)

With the below query, it is possible to make the backtrace using joins. Line 6 will find the record holding the parent group of the selected group as the temporary record bt1. Line 7 will then use the parent group id from bt1 to find this group as bt2, and so on.

1
2
3
4
5
6
7
8
9

SELECT groups.gid, groups.title, 
	bt1.gid AS 'gid-1', bt1.title AS 'title-1', 
	bt2.gid AS 'gid-2', bt2.title AS 'title-2', 
	bt3.gid AS 'gid-3', bt3.title AS 'title-3'
FROM groups
	LEFT JOIN groups AS bt1 ON bt1.gid = groups.pgid
	LEFT JOIN groups AS bt2 ON bt2.gid = bt1.pgid
	LEFT JOIN groups AS bt3 ON bt3.gid = bt2.pgid
WHERE groups.gid IN (1,2,3,4,5);

The result is

+-----+---------+-------+---------+-------+---------+-------+---------+
| gid | title   | gid-1 | title-1 | gid-2 | title-2 | gid-3 | title-3 |
+-----+---------+-------+---------+-------+---------+-------+---------+
|   1 | Level 1 |  NULL | NULL    |  NULL | NULL    |  NULL | NULL    |
|   2 | Level 2 |     1 | Level 1 |  NULL | NULL    |  NULL | NULL    |
|   3 | Level 3 |     2 | Level 2 |     1 | Level 1 |  NULL | NULL    |
|   4 | Level 4 |     3 | Level 3 |     2 | Level 2 |     1 | Level 1 |
|   5 | Level 5 |     4 | Level 4 |     3 | Level 3 |     2 | Level 2 |
+-----+---------+-------+---------+-------+---------+-------+---------+
5 rows in set (0.00 sec)

This is not really a recursive call as the title says, but the result is the same, though much faster :)

Update: Apparently I was to tired when I wrote this, a lot faster method is like Søren mentions: abs($a-$b) :)

Install Eclipse Galileo from repository:

sudo apt-get install eclipse

A number of dependencies are required inside Eclipse, which has to be added. Start Eclipse from the menu, and select Help > Install new software... The below list of update sites has to be added, which is done be typing the URL in "Work with", click Add and then type the name in the name field followed by Ok. Do this for the below update sites (name followed by URL):

EMF, http://download.eclipse.org/modeling/emf/updates/releases/
MyLyn, http://download.eclipse.org/tools/mylyn/update/e3.4/
GEF, http://download.eclipse.org/tools/gef/updates/releases/
DLTK, http://download.eclipse.org/releases/galileo/
Webtool, http://download.eclipse.org/webtools/updates/

PDT
Add http://download.eclipse.org/tools/pdt/updates/2.0/ with name PDT. Open "PDT SDK 2.1.2" and select "PHP Development Tools (PDT) Runtime Feature", click Next twice, accept the license and click Finish.

Subclipse
SVN integration (or one of them) in Eclipse is called Subclipse and is installed through update sites as well. Select Help > Install new software... and add http://subclipse.tigris.org/update_1.6.x into the "Work with" field and click Add type "Subclipse" in name and click Ok. Select all three options and click Next, Next, accept License and click Finish.

Checking out a project
Select File -> New -> Other in the new window select SVN -> Checkout Projects from SVN and click Next.

Select "Create a new repository location", click Next. Type SVN repository in URL, click Next. Type username and password if required. Select the part of the repository containing the project, click Finish.

If the repository not already holds project settings for Eclipse, select "Check out as a project configured using the New Project Wizard" and click Finish. In the New Project Wizard select PHP -> PHP Project and click Next. Give the project a name and you are ready to go - have fun! :)

$foo = "bar\"";

the highlightning ignores \" and start looking for the ending of the "".

This page gives the answer to my problem.

In Ubuntu Feisty Fawn, with jEdit installed with the Java-installer, the file is here:

/usr/local/share/jedit/4.3pre9/modes/php.xml