Writing Extensible Plugins in WordPress

#WCTO2013

About Me

Imran Nathani What I do?:

Team lead at Shaw Media for GlobalNews.ca

Past Experience:

For 6 yrs I have been developing print and broadcast news websites.

Of which 4 years, I have spent exclusively developing on WordPress VIP.

Extensibility

is notUsability

Usability

Target audience : All WordPress users

Expectations: Options Page, Shortcodes, Widgets etc.

Extensibility

Target audience: Developers

Expectations: ?????

What is an

extensible

plugin?

A plugin that can be modified and extended beyond its original purpose by another plugin or theme without modifying

original plugin.

Why write an extensible plugin?

Saves time Increases code portability Makes extra money $-) Reduces documentation

Helper function

s

“Helps” re-use code “Helps” make code easier to read

Hooks

What are hooks ?

Traditional function call

What are hooks ?

Wordpress Hook call

What are hooks ?

Wordpress hook call ( Multiple )

What are hooks ?

Hooks are placeholders for

code.

Types of hooks

Action hook

Extending methods

Filter hook

Extend values

Returns a value Returns nothing

do_action( … ) apply_filters( … )

Action hook

Wherever an action hook is placed, it will execute any code that has been “hooked” to it.

Actionhookusage

Usage A :

do_action( ‘hook-name’ );

Usage B:

do_action( ‘hook-name’ , $arg1, $arg2, … );

Usage C:

do_action_ref_array( ‘hook-name’ , $array );

Actions

Utility functions add_action(..)

remove_action(..)

remove_all_actions(..)

has_action(..)

did_action(..)

Actions

Action placements Before a task After a task Append mark up

Actions

Core actions publish_post save_post wp_head wp_foot

ActionsDEMO

Filter hooks

Wherever a filter hook is placed, it will manipulate any value that has been passed into with the function “hooked” to it

Filter hook usage

Usage A :

$value = apply_filters( ‘hook-name’ , $value )

Usage B :

$value = apply_filters( ‘hook-name’ , $value, $args, .. )

Filters

Utility functions add_filter(…)

remove_filter(…)

remove_all_filters(...)

has_filter(…)

current_filter( … )

FiltersFilter placements Before using values

Before value set up

Before returning values

Filters

Core filters the_title

the_excerpt

post_link

the_date

FiltersDEMO

Tips &

Tricks

Improve efficiency

Tips &

Tricks

Improve efficiency

Tips &

Tricks

Prefix hook names

Tips &

Tricks

Do not over extend!

Tips &

Tricks

Validate returns

Tips &

Tricks

Combine Filters

Tips &

Tricks

Combine Filters

Tips &

Tricks

Localize scripts with Filters

Tips &

Tricks

Localize scripts with Filters

Good reads

Wordpress Codex ( How to? )

Wordpress Core ( Why to? )

Questions?