WordPress offers easier way to store optional values in the database. You can also retrieve those optional values and get back to them. You just need to know the name of the optional value that you want to retrieve.

Here is an example for that

For adding a new option or updating a new option you can use the following code

 PHP | 
 copy code |
?
 
1
<?php
2
    $custom_topic_title_options='Replace: ';
3
    update_option('custom_topic_title',$custom_topic_title_options);
4
?>

For retrieving option value from the database use the following code

 PHP | 
 copy code |
?
 
1
<?php
2
$replace=  get_option('custom_topic_title', '');
3
?>

Here is a list of few functions available in WordPress to determine about URL paths in plugin development

• plugin_dir_path($plugin_file) : The full plugin path. I can use _FILE_ php constant instead of $plugin_file too. For example , To use a JavaScript file located at JS foler we have to use like below 

   PHP | 
   copy code |
  ?
   
  1
  <?php
  2
  plugin_dir_path(_FILE_)."/js/myjavascript.js";
  3
  ?> 

• plugins_url() : URL path to plugins directory
• includes_url () : URL path to include directory
• content_url() : URL path to content directory
• admin_url() : URL path to admin directory
• site_url() : URL path to WordPress installed directory
• home_url() : The specified URL path to homepage

These are the common information needed that needs to be placed above the wordpress plugin php file in the form of comments

• Name : Name of the plugin
• Description :  Description about the plugin
• Plugin URI : The URL of the plugin from where we get the information and download it
• Version : The version of the plugin
• Author : The name of the plugin author
• Author URI : URL of author’s website
• License :  The license agreement of plugin

Here is a example header information for a plugin

 PHP | 
 copy code |
?
 
01
<?php
02
/* 
03
Name : My Plugin
04
Plugin URI : http://www.wordpresssources.com
05
Description: This is a plugin by Mahesh
06
Version : 1.0
07
Author : Mahesh
08
Author URI : http://wordpresssources.com
09
Licence : GPLv2
10
*/
11
?>

Suppose you want to write a plugin called “plugin_name” then the file structure must be as below

• Directory “plugin_name” : Contains all the plugin files needed Inside this plugin we need the following fiile structure
  • File “plugin_name/plugin_name.php” : The main plugin file. This has code to execute the plugin
  • Folder “plugin_name/css” : For storing css stylesheets needed for the plugin
  • Folder “plugin_name/js” : For storing Javascript files needed for the plugin
  • Folder “plugin_name/images” : For storing images needed for the plugin
  • Folder “plugin_name/includes” : The additional include files needed for the plugin

This is one of simple approaches in writing a plugin

I was looking for a nice plugin for displaying code snippet in my wordpress blog. I found a great list of such plugins through this http://blog.templatemonster.com/2011/04/15/wordpress-plugins-code-snippets-displaying/

However out of the fifteen plugins listed out there, I liked only 3 of them

1. Developer Formatter

2. Google Syntax Highlighter

3. Syntax Highlighter Evolved

The first one depends on the GeSHI highlight system and does the syntax highlighting at the server side. The later two does it on the client side by Alex Gorbatchev’s Syntax Highlighting code. 

All the three supports many number of programming languages

Alex Gorbatchev’s Syntax Highlighting code

I choose the first one because it’s on the server side. Although it may affect server performance with better caching plugins like Quick Cache you can always have a performance gain over others.

Hence my choice is to go for Developer Formatter

You can apply a filter in a wordpress website easily

Suppose you want your name to be added to the end of site title you can use a filter

1. Use add_filter function to register the filter function
2. Define the filter function which takes the input parameter as value to be filtered
3. Return the filtered value of the function

 PHP | 
 copy code |
?
 
1
<?php
2
 
3
add_filter('wp_title', 'title_filter',10,2);
4
 
5
function title_filter($title,$postattr){
6
$title=$title." | Myname";
7
return $title;
8
}
9

Here in the add_filter function parameter 3 signifies the weight of the plugin and 2 defines the number of parameters it takes

You can add a function in the class too.. using the array attribute

 PHP | 
 copy code |
?
 
01
<?php
02
 
03
add_filter('wp_title',array('MyClass','title_filter'),10,2);
04
 
05
class MyClass{
06
  function title_filter($title,$postattr){
07
    $titile=$title." | ". "Myname";
08
    return $title;
09
    }
10
}

You can add a shortcode to your wordpress site very easily using a function

1. Use the add_shortcode function to register the shortcode function
2. Define the shortcode function
3. Return a value in shortcode function to replace the shortcode value

 PHP | 
 copy code |
?
 
1
<?php
2
add_shortcode('Myshortcode', 'shortcode_function');
3
 
4
function shortcode_function($attr){
5
 
6
return "MyShortcode has been replaced by shortcode function";
7
}
8
 
9
?>

You can also use functions within a class as shortcode function too. For the just use the shortcode function name as array with first element in array signifying classname and second one defines the class function

 PHP | 
 copy code |
?
 
01
<?php
02
 
03
add_shortcode('MyshortcodeinClass', array('MyClass', 'shortcode_function');
04
 
05
class MyClass{
06
  function shortcode_function($attr){
07
    return "This is the value returned by the shortcode MyShortCodeinClass";
08
  }
09
}
10
?>