In this chapter, we will build a module that will automate the process of sending a newsletter email to all of the users on our system. In Chapter 6, we looked at the email features. In this chapter, we will focus on three other important topics: building content filters, creating an action and assigning a trigger to the action, and creating a hook that other modules can implement.
Along the way, we will revisit some of the other topics we have already explored, but we will focus our attention on these three new topics. During the course of this chapter we will perform the following:
Assign a dependency to a module
Create a simple content type
Create content filter and an administrative interface for that filter
Add a new action
Define a custom hook and implement it
Revisit the mail API—this time to send a message to all users
Use the theme system to theme plain-text email
Create a trigger
This is a lot of ground to cover. But this chapter illustrates how complex...