pre

A simple dev code preprocessor.

What it does

pre is designed to copy a codebase and strip out development code from JavaScript (and other languages which support "C-style" multiline comments).

The preprocessor enacts the following rules:

• Any lines which contain the string /*PRE*/ will be removed.
• Multiline preprocessor blocks are any lines between (and including) /*PRE-START*/ and /*PRE-END*/. /*PRE-START*/ and /*PRE-END*/ must be on separate lines.

How to install

$ gem install pre-0.1.gem

How to use

$ pre {input directory} {output directory}

Why?

I built this to inline unit tests on small Javascript projects I work on. I would like to include quick and dirty tests near function definitions, but then be able to strip them out later. With pre, I can include these tests as development code marked with /*PRE*/ (or between and including lines containing /*PRE-START*/ and /*PRE-END*/) right up next to the function/object definition, reminding me to update my assertions as I update my code. The following example illustrates the intended use case.

Example

The file input/test.js

/*PRE-START*/ // This line and the following lines will be removed
function assert(trueExpression, failureMessage) {
	if(!trueExpression) {
		throw failureMessage;
	}
}
/*PRE-END*/ // This line will be removed
// This line will not be removed

// This is the function we will test with assert
function square(x) {
	return x * x;
}
// The following line will be removed
assert(square(5) === 25, "5 x 5 should be 25"); /*PRE*/

Processed with $ pre input output will produce:

// This line will not be removed

// This is the function we will test with assert
function square(x) {
	return x * x;
}
// The following line will be removed