Monday, December 10, 2012

An Approach to Illiterate Programming: doc-code-merge

It's very common to embed code examples in technical documentation. However, doing so is kind of painful. First of all, the environment you use to edit the documentation may not be the same as the environment you use to write code. For instance, I generally use Dart Editor to write Dart code, but I use Sublime Text 2 to edit documentation written in HTML or Markdown. Secondly, it's difficult to run unit tests or use dart_analyzer if the code is trapped in documentation. This is a big problem for us on the Dart project because we move pretty quickly, and we want to make sure our documentation is always 100% correct. I've created a tool called doc-code-merge to solve this problem.

doc-code-merge is the opposite of what Donald Knuth labelled Literate Programming. doc-code-merge lets you write your documentation and your code examples completely separately. When you run doc_code_merge.dart, it makes a copy of your documentation with all the examples merged in. The Pragmatic Programmers mentioned using a similar tool when writing The Pragmatic Programmer: From Journeyman to Master, so the idea has probably been around for a while.
Using doc-code-merge is easy. Start by writing some documentation such as:
Then, write some code such as:
Now, run doc_code_merge.dart:
This results in:
Easy peasy! doc-code-merge automatically handles things like indenting code blocks when generating Markdown and HTML escaping code when generating HTML.

Although doc-code-merge is written in Dart, it'll work with almost any programming language and with almost any type of documentation as long as the documentation is written in text such as HTML or Markdown. We're hoping to make use of it for the Dart web site, dartlang.org, and for our book on Dart, Dart: Up and Running.

If you're interested in using doc-code-merge, check out the README. As always, we invite you to join the Dart mailing list and ask questions on Stack Overflow.