Rake

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rake Not 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. 6


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

• • •

FileUtils clean clobber

namespace multitask

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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} 25


Clean/Clobber • • •

require 'rake/clean'

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

Use a pair of file lists: CLEAN and CLOBBER. You can then add items to the file lists with expressions like CLEAN.include('*.o').

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Built In Tasks • GemPackageTask (in Ruby Gems now) • PackageTask • RdocTask (in Rdoc now) • TestTask 27


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! 28


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 - Rake

http://rake.rubyforge.org/

• Martin Fowler - Using the Rake Build

Language http://martinfowler.com/articles/rake.html

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

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Thank You • tyler.bird@gmail.com • @filmprog • filmprog.com

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