Rake
The Familiar Stranger
Josh Nichols technicalpickles.com

What is Rake?
Ruby Make
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Ruby what?
A Ruby build tool
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Which means...?
A tool for automating tasks on the command
line using plain ol’ Ruby
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What would you use Rake for?
• Define a task
• Make the task do something, maybe have it depend on
other tasks
• You’ve probably already used it
• rake db:migrate
• rake test
Josh Nichols technicalpickles.com

Overview
• The basics of Rake
• Creating re-usable tasks for Rails
• Creating re-usable tasks for any Ruby project
• Testing
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Hello World
# Rakefile (or rakefile or rakefile.rb or Rakefile.rb)
require 'rake'
desc \"Hello World!\"
task :hello_world do
puts \"Hello World!\"
end
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rake_demo $ rake -T
(in /Users/nichoj/Projects/rake_demo)
rake hello_world # Hello World!
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rake_demo $ rake hello_world
Hello World!
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Defining tasks
• desc
• provide a human readable description for a task you're
about to define
• rake -T doesn’t show the task without this
• task
• provide a task name (can be a symbol or string)
• provide a block
• it's just ruby, yo
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Defining tasks: playing with the
filesystem
• FileUtils module is included
• cd, pwd, mkdir, mkdir_p, rmdir, ln, ln_s, ln_sf, cp, cp_r,
mv, rm, rm_r, rm_rf, install, chmod, touch
• FileList lets you specify a pattern for files/directories,
then use it as an Enumerable
• FileList['**/*.rb'].each {|f| puts f }
Josh Nichols technicalpickles.com

Defining tasks: playing with the
filesystem
require 'rake'
desc \"Clean the build directory\"
task :clean do
rm_r 'build'
end
desc \"Make a backup of all ruby files\"
task :backup do
FileList['**/*.rb'].each do |f|
cp f, \"#{f}.bak\"
end
end
Josh Nichols technicalpickles.com

Dependencies between tasks
• Easily declare a dependency on another task
• A task that is depended on will only be run once... even
if you run multiple times
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Dependencies between tasks
require 'rake'
task :give_presentation => :prepare_presentation do
puts \"So there's this thing called 'Rake'...\"
end
task :prepare_presentation => :take_nap do
puts \"Just preparing, nothing to see here, move along\"
end
task :take_nap do
puts \"zzzzzzzzzzzzzzzzzzz\"
end
Josh Nichols technicalpickles.com

rake_demo $ rake give_presentation
(in /Users/nichoj/Projects/rake_demo)
zzzzzzzzzzzzzzzzzzz
Nothing to see here, move along
So there's this thing called 'Rake'...
Josh Nichols technicalpickles.com

rake_demo $ rake take_nap give_presentation
zzzzzzzzzzzzzzzzzzz
Nothing to see here, move along
So there's this thing called 'Rake'...
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Group related tasks
• Would be annoying to have a flat namespace
• This isn’t C!
• Rake has the concept of namespaces
• rake namespace:task_name
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Define a namespace
require 'rake'
namespace :presentation do
task :give => :prepare do
puts \"So there's this thing called 'Rake'...\"
end
task :prepare => :take_nap do
puts \"Just preparing, nothing to see here, move along\"
end
end
task :take_nap do
puts \"zzzzzzzzzzzzzzzzzzz\"
end
Josh Nichols technicalpickles.com

Extending tasks: more
dependencies
• Just declare the task again, but with dependencies
• These get added to whatever dependencies
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Moar dependencies
namespace :presentation do
task :give => :prepare do
puts \"So there's this thing called 'Rake'...\"
end
task :prepare => :take_nap do
puts \"Just preparing, nothing to see here, move along\"
end
task :prepare => :watch_tv
end
task :watch_tv do
puts \"Previously on Heroes...\"
end
task :take_nap do
puts \"zzzzzzzzzzzzzzzzzzz\"
end
Josh Nichols technicalpickles.com

Using off the shelf tasks
• Rake comes with a few bundled
• Rake::GemPackageTask, Rake::PackageTask,
Rake::RDocTask, Rake::TestTask
• Just instantiate an instance in your Rakefile
Rake::TestTask.new do |t|
t.libs << 'lib'
t.pattern = 'test/*_test.rb'
t.verbose = false
end
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Cue live coding
... cuz I ran out of time to make slides
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Done, and done.
Josh Nichols technicalpickles.com

What’s got two thumbs and is
available for hire?
http://technicalpickles.com/resume
josh@technicalpickles.com
Josh Nichols technicalpickles.com