1Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Rake

2Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Automated Build• Any non-trivial project needs facility to

automate builds– Routine common tasks that need to be

carried out several times a day

• Not very efficient to do manually and also error prone

• Rake is the make utility for Rails

3Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

What does a make file have?• Typically a make file has

– Commands or tasks

– Dependency between the tasks

– A way to specify which tasks to execute (selectively or all)

– Tasks only execute if necessary

4Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

make vs. ant• Even though similar quite some

differences

• ant is task based– You specify tasks and instructions to execute

• make allows file type based specification– You can say that a type of file needs to be

built based on another type of file– make will check for timestamp of these files

and decide if it should be built

5Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

What’s special about Rake?• Ant for Java (NAnt for .NET) uses xml• Jim Weirich’s Rake uses ruby!• Makes it easier to write – you are not

switching languages – feels natural• If you know Ruby, you simply read it and

you get it!• Rake is a internal Domain Specific

Language which uses the Ruby syntax• Rake is very easy to extend – write Ruby

code

6Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Let’s Give It a Try

7Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Rake Conventions• Rake uses rakefile.rb by default when you

type rake

• => is used for dependency/pre-requisites

• :default is the task that will be executed, err, by default

8Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Rake Dry Run• Allows you to see what Rake will do

• -- trace option will trace the task calls as it executes

9Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Rake prerequisites• You can find what the pre-requisite for

tasks are using the -P option

10Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Task and description• You can write a description for task and

check those out using –T option

11Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Prerequisite Specification• You can specify when you define a task• You can also specify separately

12Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

file tasks• In addition to tasks like we saw so far,

you can define file tasks

• File tasks (like good old make) specify the input output file and pre-requisite input file

• Checks time stamp of output file and if it is earlier than input file, task is executed

13Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Using file

14Venkat Subramaniam – svenkat@cs.uh.eduVenkat Subramaniam – svenkat@cs.uh.edu

Rake and Rails• Rails make great use of Rake

• Allows you to run different tasks– Tests– Cloning database– …

• One way to learn rake is to study the rake files in Rails