Drupal 7 Module Development

There are half a dozen hooks in the Block API, providing opportunities to do
everything from declaring new blocks to altering the content and behavior of
existing blocks. For our simple module, we are going to use two different hooks:
• hook_block_info(): This is used to tell Drupal about the new block or
blocks that we will declare
Chapter 2
• hook_block_view(): This tells Drupal what to do when a block is requested
for viewing
One thing to keep in mind, in the context of the Block API as well as other APIs is
that each module can only implement a given hook once. There can be only one
first_block_info() function.
Since modules should be able to create multiple blocks, that means that the
Block API must make it possible for one block implementation to manage multiple
blocks. Thus, first_block_info() can declare any number of blocks, and
first_block_view() can return any number of blocks.
The entire Block API is documented in the official Drupal 7
API documentation, and even includes an example module:
http://api.drupal.org/api/drupal/developer--
examples--block_example.module/7.
To keep our example simple, we will be creating only one block. However, it is good
to keep in mind that the API was designed in a way that would allow us to create as
many blocks as we want.
Let's start with an implementation of hook_block_info().
The block info hook
All of the functions in our module will go inside of the first.module file—the
default location for hook implementations in Drupal. Before, we created
first_help(), an implementation of hook_help(). Now, we are going to
implement the hook_block_info() hook.
The purpose of this hook is to tell Drupal about all of the blocks that the module
provides. Note that, as with any hook, you only need to implement it in cases where
your module needs to provide this functionality. In other words, if the hook is not
implemented, Drupal will simply assume that this module has no associated blocks.
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