Once you get into serious Drupal module development, you'll realize that it would be really helpful if you could do several things during the module development process, including clearing the cache, rebuilding the menus, error logging (logging errors to a file, in particular), and so on. Fortunately, with Drupal's really large developer ecosystem, other Drupal programmers have already created some great modules to help you along in the coding process.
Here's a list of the Drupal developer modules I currently use, or have used.
The Drupal Devel module makes a lot of useful functions available to you in a Drupal block, such as:
Here's a link to the Drupal Devel module on Drupal.org.
The Drupal Coder module provides automated code reviews of your Drupal module. The Coder module adds a "Code Review" link next to your modules in the "admin/build/modules" list.
As a quick test of the latest Coder module, I just ran its Drupal code review function against a Drupal module I'm currently developing, and happily just got some minor warning messages.
Here's a blurb from the Coder module documentation on what it does:
Coder provides helpful hints without false positives, but offers no guarantee for creating good code. You are the final arbitrar. If in doubt, read the Drupal documentation (see review links below and api.drupal.org).
Here's a link to the Drupal Coder module on Drupal.org.
As its name implies, the Drupal Schema module does a lot of nice work for you related to your Drupal database schema. If you're written a Drupal module before, and that module needed to create new database tables, you'll know that the Drupal Schema module is very helpful for generating the necessary Drupal "install" file for your Drupal module.
Once it's installed, the Drupal Schema module can be accessed from your Drupal menu system, or from this URI path:
You can find out more information about the Drupal Schema module on Drupal.org.
The Drupal Module Builder module (module_builder) ...
A module which auto-generates a skeleton or "scaffolding" for a module, along with hints on how to fill them in. Useful for newbie developers to learn how hooks work, and seasoned developers who are too lazy to look up what arguments a function has to take.
Once installed, the Module Builder module is available on your system at a URL like this:
Here's a link to the Drupal Module Builder module on Drupal.org.
The Drupal File Logger module is something I was about to write for myself, when I discovered it. From the module documentation page:
File logger is a lightweight module that allows developers to configure a log file from within Drupal and dump variables to it from within a running Drupal app.
The primary function of the File Logger module is to support Drupal debugging, and it avoids the awkwardness of dumping variables either to the console or to the watchdog table.
Here's a link to the Drupal File Logger module on Drupal.org.
I hope this list of Drupal developer modules has been helpful. If you're a Drupal programmer, and know of other good modules for developers, feel free to leave a note in the Comments section below.