Interesting Facts on Drupal Module Development

I am reading Drupal 7 Module Development by

Matt Butcher, Greg Dunlap, Matt Farnia, Larry Garfield, Ken Rickard and Jon Albin Wilkins.

Inspired by the book, some Interesting Facts on Drupal Module Development that I wanted to share

1. What is the hook implementation in Drupal?
   EVENT Triggers in drupal: The Hook implementation is a function that follows a certain naming pattern in order to indicatie to Drupal that it should be used as a callback for a particular event in the Drupal System.
   
   In most cases ensure the hook implementations reside within the main .module file.

2. Placing your Custom modules:
   OPTION1: The convention that we follow is to place both Contributed and Custom modules under sites/all/modules directory. All the custom modules are placed with in sites/all/modules/custom.

OPTION2: The second approach could be to have all Contributed modules under
sites/all/modules/contrib and any Custom modules under sites/all/modules/custom. This may not be a good solution as in Drupal 7 when you use Drush, the modules are automatically installed under sites/all/modules.

OPTION3: The approach I read in the book seems really neat. Place all Contrib modules under sites/all/modules and all custom modules under sites/default/modules.
The main advantage being, it brings a clear separation between the modules maintained by us and those by the community.

But in the case of a multisite installation where there is a need to share the custom modules across installations choose OPTION1

3. The .info file in any module always starts with a $Id$. Have you wondered why?
   This is a placeholder for the Version control system to store information about the file. ( When the file was last checked in and by who)
   With the new GIT integration alive, this should be on the way out.
   
   
4. Follow Doxygen-style commenting (/**  */)
   @file decorator for doc-block should be the first doc block of any module
   Syntax: Begin with a single sentence Description of the module, followed by  a blank line and then followed by a one or more paragraph description of the module.
   ALL DOCS MUST BE WRITTEN IN GRAMATICALLY CORRECT AND PUNCTUATED SENTENCES.
   
   

5. 
   $variable = ‘This is a string’ ;
   t($variable) ;

   
   
   Why wouldn’t translation system work above?
   
   Automated Translation run, the code doesnot execute it only simply reads.
   
   
6. Once a module is installed, Drupal caches the content of the .info file. Revisit the module page to force Durpal to refresh this information.
   
   
7. Drupal arrays - terminate large multiline arrays with a comma: This is to help in avoiding syntax errors while adding or removing from a large array.
   This can not be extended to drupal js arrays.
   
   
8. 2 Most powerful Enhancements in Drupal 7
   
   
1. PDI – PHP Data Object library integration in Durpal 7: This  library is an abstraction layer that supports numerous database layer. This provides the capability for Drupal 7 to support beyond MYsql. Postgre-sql to Oracle and
2. Fields and Entities

                                                             i.      Field system: Bring with it CCKs functionality in the core

                                                          ii.      Entity System: make sit possible to define structures data types that are not NODES!