WordPress 2.5 comes with a very handy API that plugin authors should love: shortcodes, ie. BBcode-like tags, that are parsed when found in post contents. The API is very easy to use, and well done enough that it's relatively foolproof.<\/p>\n
The API allows for all the possible combinations and forms you'd think of: selfclosing or open tags, attributes with single or double quotes.<\/p>\n
[tag]\r\n[tag \/]\r\n[tag attribute="value" \/]\r\n[tag attr1='value1' attr2="value2" ]\r\n[tag]enclosed content[\/tag]\r\n[tag attr="value"]enclosed content[\/tag]<\/code><\/pre><\/div>\nThe Concept<\/h2>\n
First, you have to define a function that will take care of your shortcodes, their potential attributes, and any enclosed content:<\/p>\n
function my_shortcode_func($attr, $content) {\r\n\t\/\/ $attr is an array of $key=>$value pairs\r\n\t\/\/ $content is a string containing the enclosed content\r\n\t\/\/ ... do something with $attr and $content\r\n\t\/\/ return the expected result\r\n}<\/code><\/pre><\/div>\nThen, to register your new shortcode so that [tag attr="value"]content[\/tag] is processed as wished by my_shortcode_func(), you just add:<\/p>\n
add_shortcode('tag', 'my_shortcode_func');<\/code><\/pre><\/div>\nAll API functions<\/h2>\n
The API comes with a set of mostly self explanatory functions you can use:<\/p>\n
add_shortcode('tag', 'function_name'); \/\/ register a new shortcode\r\nremove_shortcode('tag'); \/\/ unregister\r\nremove_all_shortcodes(); \/\/ just as it says\r\n$return = do_shortcode($content); \/\/ apply shortcodes to content without echoing anything<\/code><\/pre><\/div>\nExamples<\/h2>\n[tag1] → Some Longer Text<\/h3>\nfunction shortcode_example1() {\r\n return 'Some Longer Text';\r\n}\r\nadd_shortcode('tag1', 'shortcode_example1');<\/code><\/pre><\/div>\n[tag2 param="something"] → Some Longer Text and something<\/h3>\nfunction shortcode_example2($attr) {\r\n return 'Some Longer Text and '.$attr['param'];\r\n}\r\nadd_shortcode('tag2', 'shortcode_example2');<\/code><\/pre><\/div>\n[tag3]something[\/tag3] → You just said "something", didn't you ?<\/h3>\nfunction shortcode_example3($attr, $content) {\r\n return "You just said '$content', didn't you ?";\r\n}\r\nadd_shortcode('tag3', 'shortcode_example3');<\/code><\/pre><\/div>\n[tag4 any attribute]something[\/tag4] → Attributes: {list of attributes}. Content: {content}<\/h3>\nfunction shortcode_example4($attr, $content) {\r\n\t$attributes = '';\r\n\tforeach ($attr as $key=>$value) {\r\n\t\t$attributes .= "$key: $value\\n";\r\n\t}\r\n return "Attributes: $attributes<br\/>Content: $content";\r\n}\r\nadd_shortcode('tag4', 'shortcode_example4');<\/code><\/pre><\/div>\nExperiment and read more<\/h2>\n
Test and experiment: all the examples above are gathered into this simple Shortcodes plugin example<\/a> (rename as shortcodes.php and put in your plugin directory). It's interesting to try to break things with unexpected attributes or enclosed content: the API is pretty foolproof and should ignore things just as you'd thought it should.<\/p>\n