icing

icing adds dependency management and interactive building to CoffeeScript's cake command and Cakefiles.

Installation

Install with npm: npm install icing

To add icing to a Cakefile add include the line:

require 'icing'

There are two significant ways icing breaks backwards compatibility with pre-existing Cakefiles.

1. Using the invoke function to call other tasks is replaced by dependencies.
2. Task should now end by calling this.finished() or this.failed('Error message') to signify the completion of a task.

Built-in Command Line Options

-w, --watch,  Interactively build to target as source files change
-v, --verbose Enable verbose output mode

Example Cakefile

task 'js:coffee', 'Compile Coffee Script', ['src/*.coffee'],
    outputs: -> 
        for file in this.filePrereqs
            file.replace /src\/(.*)\.coffee/, 'lib/$1.js'
    recipe: -> 
        this.exec "coffee -c -o lib/ #{this.modifiedPrereqs.join(' ')}"

task 'js:run', 'Run all compiled scripts', ['outputs(js:coffee)'], 
    outputs: ->
        for file in this.filePrereqs
            "output/#{file.replace /\//, '_'}"
    recipe: ->
        commands = for file in this.modifiedPrereqs
            "node #{file} > output/#{file.replace '/', '_'}"
        commands = ['mkdir -p output/'].concat commands
        this.exec commands

task 'all', 'Run all tasks', ['task(js:run)'], ->
    console.log 'Done.'
    this.finished()

API

icing introduces a new form of the task function that has four parameters:

task target, description = '', prereqs = [ ], recipe

The target and description strings are unchanged from cake. prereqs is an array of strings that can refer to three different kinds of prereqs:

1. Filenames. Filename strings are globbed, i.e. src/*.coffee
2. Task completion. task(target) creates a prereq on the completion of a task.
3. Task outputs. outputs(target) uses the file outputs of another task as prereqs.

recipe should be an object that responds to the methods recipe and outputs. When recipe is just a function, as it is in traditional Cakefiles, it is turned into an object whose recipe method is that function and whose outputs returns []. Like with Cakefiles these methods will be passed the options array containing command-line options. Unlike Cakefiles, the this context of the methods contains callbacks and data.

outputs method's this context contains:

• filePrereqs - array of filenames, post-globbing, that are direct prereqs to the rule. This array is often mapped to an array of outputs.
• recipe - the object outputs and recipe methods are defined on
• prereqs - array of unprocessed prereqs
• target - the name of the task

recipe method's this context contains:

• exec(command) - helper method for command line edecution that can take a single string command or an array of commands. It will call the commands one-by-one and upon successful completion of all commands will automatically call the finished callback. Else it will call the failed callback.
• finished() - callback to signal successful completion of task
• failed(msg) - callback to signal unsuccessful completion of task
• filePrereqs - array of strings of prerequisites. Often used as inputs to commands executed. In this context prereqs have already been globbed so ['src/*.coffee'] could become ['src/a.coffee','src/b.coffee'].
• outputs - array of strings resulting from calling the outputs method of the recipe object.
• modifiedPrereqs - if prereqs and outputs are both defined this is the list of files that have been modified more recently than their outputs.

TODO

• In interactive / watch mode poll globbed locations to pick-up on new files and rebuild dependency graph when detected.

In interactive / watch mode rather than traverse entire task set pick out

the subgraph between the modified source and the target to more efficiently recompute large dependency graphs.