Rake: Not Your Father's Build Tool

rakeNot your father’s build tool

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whatchutalk’nboutwillis

• Where it came from

• What it’s related to

• How to use it

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What’s in a name?

• Usually the first thing people learn about rake is the etymology of the name: “Ruby Make”.

• But it’s much more than a catchy turn of phrase.

• It’s a fully featured Build Language. That almost never existed...

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Ruby Version of Make?

• Jim tells the birth of rake as code he never intended to write.

• It started with a simple itch to scratch...

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Jim Thought “What if...”

"What if you could specify the make tasks in Ruby, like this ..."

task "build" do

java_compile(...args, etc ...)

end

"The task function would register "build" as a target to be made,

and the block would be the action executed whenever the build

system determined that it was time to do the build target."

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100 Lines Later

• It worked!

• Rake’s prototype lives in the repo: doc/proto_rake.rdoc

• But it didn’t have timebased file dependencies... so back to the text-editor.

• And the rest is in the commit history.

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A Build Language

• The basic unit of a build language are tasks.

• A build has source files that it uses to produce a desired product.

• The two most common other build languages are make and ant.

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Comparison

make ant rake

Imperative Style Imperative Style Dependency Based

External DSL External DSL Internal DSL

Custom Syntax XML based Syntax Ruby Syntax

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Imperative Style

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Imperative Style

• Both the code_generation methods will be called during test.

• At best that will waste time.

• At worst that can produce undesired results.

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Dependency Based

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Dependency Based

• A dependency based system gives the test method the power to evaluate what prerequisites it has.

• Then because ruby can evaluate the code without running it, it can prepare it to be run in the correct order that will only run each task once.

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Comparison

make ant rake

Imperative Style Imperative Style Dependency Based

External DSL External DSL Internal DSL

Custom Syntax XML based Syntax Ruby Syntax

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External vs Internal DSL

• With make and ant you need to use external scripts or nasty syntax to be creative.

• Rake can use full power of Ruby at any time.

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Hello World

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Building Blocks of Rake

• task

• file

• directory

• namespace

• multitask

• FileUtils

• clean

• clobber

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task

In the DSL of rake, a task is a method that takes two arguments. The first argument is a hash, and the second is a block.

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task dependencies

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file

Rake file tasks are most similar to tasks in make. They get run only when needed. File tasks are declared using a string rather than a symbol. The following file task creates a executable program (named prog) given two object files name a.o and b.o.

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directory

It is common to need to create directories upon demand. The directory convenience method is a short-hand for creating a FileTask that creates the directory.

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directory

The directory method does not accept prerequisites or actions, but both prerequisites and actions can be added later.

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namespaces

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multitask

Multitask can help you save time by running tasks in your build that are safe to run in parallel.

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multitask

It even has the ability to determine any prerequisites that need to be run before hand. It will complete this prep_for_copy only once then the three tasks would begin to run together.

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FileUtils

• Use the FileUtils module and rake gives you the most common filesystem commands:

• cd, pwd, mkdir, mkdir_p, rmdir, ln, ln_s, ln_sf, cp, cp_r, mv, rm, rm_r, rm_rf, install, chmod, touch

• Create a map of files with FileList:

• FileList[‘**/*.rb’].each {|f| puts f}

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Clean/Clobber

• require 'rake/clean'

• Use a pair of file lists: CLEAN and CLOBBER.

• You can then add items to the file lists with expressions like CLEAN.include('*.o').

• Remember that the clean task removes everything in the clean list, and clobber removes everything in both lists.

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Built In Tasks

• GemPackageTask (in Ruby Gems now)

• PackageTask

• RdocTask (in Rdoc now)

• TestTask

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Rake & Rails

• The default task for a rails project runs your test suite.

• If you want to see how the rake tasks you enjoy with Rails are built search for .rake in the gem source.

• Because as we all know, Rails is Magic!

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rake

• Jim Weirich created in 2003.

• Similar to make and ant. With the power of Ruby.

• Hope you’ve got some ideas on how you’d like to use it.

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Credits

• Jim Weirich - Rakehttp://rake.rubyforge.org/

• Martin Fowler - Using the Rake Build Languagehttp://martinfowler.com/articles/rake.html

• Josh Nichols - Rake: The Familiar Strangerhttp://vimeo.com/2496890

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Thank You

• tyler.bird@gmail.com

• @filmprog

• filmprog.com

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