Difference between revisions of "Geeklog's way of doing things"

Revision as of 14:05, 23 May 2009

All of Geeklog's PHP files are pure PHP. PHP allows you to use PHP as a scripting language imbedded in HTML files but this is not how Geeklog does it. All of Geeklog's PHP files must have <?php as the first five characters and end with ?>. Failure to structure your Geeklog files this way will cause session and header errors. Geeklog attempts as much as possible to have only PHP code in the .php files. Two of the conventions used in Geeklog to accomplish this are the use of templates and language files.

Time will be well spent by the Geeklog plugin or block developer to become familiar with several Geeklog libraries. The following section outlines the more important or frequently used libraries, functions and standards.

lib-common.php

The Geeklog plugin or block developer should have a good understanding of lib-common.php which contains most of the display routines as well as some other general purpose routines. All of the Geeklog display routines return HTML. They do not contain echos or prints themselves. The way the Geeklog system is designed; you usually put your code between Geeklog display routines. For example: code to display a page would look like this:

$display  = COM_siteHeader();
$display .= COM_startBlock("Title of Your Block");
$display .= "Some words";
$display .= somefunction();
$display .= COM_endBlock;
$display .= COM_siteFooter(true);
echo $display;

A summary of commonly used Geeklog functions are described below but reference the lib-common.php documentation for further examples.

lib-security.php

The lib-security.php file contains the interface routines to the security system used in Geeklog. See the lib-security.php documentation. There are several SEC type functions that you may want to use in your projects. The table Commonly Used Geeklog Functions at the end of this section defines a couple of the more commonly used functions.

lib-database.php

All database access should take place through the database abstraction in lib-database.php and table names should be accessed through the $_TABLES array. The table definitions in this array will then include whatever table prefix this site is using. You should ensure that your plugin or block uses the $_TABLES['mytable'] for all database access related functions.

• Block developers and site admins installing the block need to make sure that any tables needed by a block are added to the $_TABLES array. Ensure you follow the same standard by using the $_DB_table_prefix. However, you should not edit lib-database.php. If no suitable place can be found in the block's code, the addition should be done in lib-custom.php instead.
• Plugin developers need to define their tables in the plugin config.php file (or some other suitable file belonging to the plugin, e.g. functions.inc). You have the ability to use the $_TABLES array or use your own plugin specific array to maintain the table definitions. In the latter case it's recommend that your arrays use a name such as _XX_TABLES, where XX are two letters to describe your plugin. Once the plugin is installed and enabled, the tables defined for the plugin are automatically known as globals.

lib-plugins.php

This library contains all the code used to interface your plugin or block to Geeklog. You will not call any code from here directly. The functions in this file are called by the Geeklog main programs as they are used to call all plugins and are used to resolve the plugin name and check if your plugin has a particular function. You will usually only have to look at this file to understand some nuance of the implementation. See the documentation for functions.inc and the original plugin documentation for further help.

How your Plugin or Block Interacts with Geeklog

The program lib-common.php is the key to all interaction with Geeklog. It includes all of the Geeklog code libraries.

• At the top of lib-common.php is an include of lib-custom.php. This is where you place all your block functions. They are then included when the site index.php is called.
• At the very end of lib-common.php is a check for all enabled plugins. A plugin is registered with Geeklog when it has a record in the plugins table and the field pi_enabled is 1. For all registered and enabled plugins, the code in lib-common.php will include the functions.inc file for each plugin. This is why the naming convention and location for each plugin file is strictly defined. All code libraries or configuration files your plugin needs should be included in your functions.inc. Since the plugin's config.php (if it exists) is now also included this way - via the include in functions.inc - the variables in your plugin config.php become global and can be referenced in your plugin functions.

Common Global Variables

There are a few commonly used globals within Geeklog that you will want to use and reference. The following table outlines the more frequently used ones and its recommended that these be used instead of hard coding paths and table names in your links or project code.

Commonly used Geeklog functions

The following is a list of commonly used Geeklog functions that as developers we use and recommend you become more familiar with and use in your development projects. You will find example usage of these functions throughout the Geeklog code.