h1. More Stuff


h2.  Using Gems

The purpose of the buildfile is to define your projects, and the various tasks
and functions used for building them.  Some of these are specific to your
projects, others are more general in nature, and you may want to share them
across projects.

There are several mechanisms for developing extensions and build features
across projects which we cover in more details in the section "Extending
Buildr":extending.html.  Here we will talk about using extensions that are
distributed in the form of RubyGems.

"RubyGems":http://rubygems.rubyforge.org provides the @gem@ command line tool
that you can use to search, install, upgrade, package and distribute gems. It
installs all gems into a local repository that is shared across your builds and
all other Ruby applications you may have running.  You can install a gem from a
local file, or download and install it from any number of remote repositories.

RubyGems is preconfigured to use the "RubyForge":http://rubyforge.org
repository.  You'll find a large number of open source Ruby libraries there,
including Buildr itself and all its dependencies.  RubyForge provides a free
account that you can use to host your projects and distribute your gems (you
can use RubyForge strictly for distribution, as we do with Buildr).

You can also set up your own private repository and use it instead or in
addition to RubyForge.  Use the @gem sources@ command to add repositories, and
the @gem server@ command to run a remote repository.  You can see all available
options by running @gem help@.

If your build depends on other gems, you will want to specify these
dependencies as part of your build and check that configuration into source
control.  That way you can have a specific environment that will guarantee
repeatable builds, whether you're building a particular version, moving between
branches, or joining an existing project.  Buildr will take care of installing
all the necessary dependencies, which you can then manage with the @gem@
command.

Use the @build.yaml@ file to specify these dependencies (see "Build
Settings":settings_profiles.html#build_settings for more information), for
example:

{{{!yaml
# This project requires the following gems
gems: 
  # Suppose we want to notify developers when testcases fail.
  - buildr-twitter-notifier-addon >=1
  # we test with ruby mock objects
  - mocha
  - ci_reporter
}}}

Gems contain executable code, and for that reason Buildr will not install gems
without your permission.  When you run a build that includes any dependencies
that are not already installed on your machine, Buildr will ask for permission
before installing them.  On Unix-based operating systems, you will also need
sudo privileges and will be asked for your password before proceeding.

Since this step requires your input, it will only happen when running Buildr
interactively from the command line.  In all other cases, Buildr will fail and
report the missing dependencies.  If you have an automated build environment,
make sure to run the build once manually to install all the necessary
dependencies.

When installing a gem for the first time, Buildr will automatically look for
the latest available version.  You can specify a particular version number, or
a set of version numbers known to work with that build.  You can use equality
operations to specify a range of versions, for example, @1.2.3@ to install only
version 1.2.3, and @=> 1.2.3@ to install version 1.2.3 or later.

You can also specify a range up to one version bump, for example, @~> 1.2.3@ is
the same as @>= 1.2.3 < 1.3.0@, and @~> 1.2@ is the same as @>= 1.2.0 < 2.0.0@.
If necessary, you can exclude a particular version number, for example, @~>
1.2.3 != 1.2.7@.

Buildr will install the latest version that matches the version requirement.
To keep up with newer versions, execute the @gem update@ command periodically.
You can also use @gem outdated@ to determine which new versions are available.

Most gems include documentation that you can access in several forms.  You can
use the @ri@ command line tool to find out more about a class, module or
specific method.  For example:

{{{!sh
$ ri Buildr::Jetty
$ ri Buildr::Jetty.start
}}}

You can also access documentation from a Web browser by running @gem server@
and pointing your browser to "http://localhost:8808":http://localhost:8808.
Note that after installing a new gem, you will need to restart the gem server
to see its documentation.


h2.  Using Java Libraries

Buildr runs along side a JVM, using either RJB or JRuby.  The Java module
allows you to access Java classes and create Java objects.

Java classes are accessed as static methods on the @Java@ module, for example:

{{{!ruby
str = Java.java.lang.String.new('hai!')
str.toUpperCase
=> 'HAI!'
Java.java.lang.String.isInstance(str)
=> true
Java.com.sun.tools.javac.Main.compile(args)
}}}

The @classpath@ attribute allows Buildr to add JARs and directories to the
classpath, for example, we use it to load Ant and various Ant tasks, code
generators, test frameworks, and so forth.

When using an artifact specification, Buildr will automatically download and
install the artifact before adding it to the classpath.

For example, Ant is loaded as follows:

{{{!ruby
Java.classpath << 'org.apache.ant:ant:jar:1.7.0'
}}}

Artifacts can only be downloaded after the Buildfile has loaded, giving it a
chance to specify which remote repositories to use, so adding to classpath does
not by itself load any libraries.  You must call @Java.load@ before accessing any
Java classes to give Buildr a chance to load the libraries specified in the
classpath.

When building an extension, make sure to follow these rules:

# Add to the @classpath@ when the extension is loaded (i.e. in module or class
definition), so the first call to @Java.load@ anywhere in the code will include
the libraries you specify.
# Call @Java.load@ once before accessing any Java classes, allowing Buildr to
set up the classpath.
# Only call @Java.load@ when invoked, otherwise you may end up loading the JVM
with a partial classpath, or before all remote repositories are listed.
# Check on a clean build with empty local repository.


h2. Nailgun

"Nailgun":http://www.martiansoftware.com/nailgun/index.html is a client,
protocol, and server for running Java programs from the command line without 
incurring the JVM startup overhead. 
Nailgun integration is available only when running Buildr within JRuby.

Buildr provides a custom nailgun server, allowing you to start a single JVM
and let buildr create a queue of runtimes.
These JRuby runtimes can be cached (indexed by buildfile path) and are 
automatically reloaded when the buildfile has been modified.
Runtime caching allows you to execute tasks without spending time creating 
the buildr environment. 

Start the BuildrServer by executing

{{{!ruby
$ jruby -S buildr -rbuildr/nailgun nailgun:start
}}}

Server output will display a message when it becomes ready, you
will also see messages when the JRuby runtimes are being created,
or when a new buildr environment is being loaded on them.
After the runtime queues have been populated, you can start calling
buildr as you normally do, by invoking the $NAILGUN_HOME/ng binary:

{{{!sh
# on another terminal, change directory to a project.
# if this project is the same nailgun:start was invoked on, it's 
# runtime has been cached, so no loading is performed unless 
# the buildfile has been modified. otherwise the buildfile 
# will be loaded on a previously loaded fresh-buildr runtime
# and it will be cached.
cd /some/buildr/project
ng nailgun:help                      # display nailgun help
ng nailgun:tasks                     # display overview of ng tasks
ng clean compile                # just invoke those two tasks
}}}

Some nailgun tasks have been provided to manage the cached runtimes, 
to get an overview of them execute the @nailgun:tasks@ task.

Be sure to read the nailgun help by executing the @nailgun:help@ task.


h2. Eclipse, IDEA

If you're using Eclipse, you can generate @.classpath@ and @.project@ from
your Buildfile and use them to create a project in your workspace:

{{{!sh
$ buildr eclipse
}}}

The @eclipse@ task will generate a @.classpath@ and @.project@ file for each
of projects (and sub-project) that compiles source code.  It will not generate
files for other projects, for examples, projects you use strictly for
packaging a distribution, or creating command line scripts, etc.

If you add a new project, change the dependencies, or make any other change to
your Buildfile, just run the @eclipse@ task again to re-generate the Eclipse
project files.

If you prefer IntelliJ IDEA, you can always:

{{{!sh
$ buildr idea
}}}

It will generate a @.iml@ file for every project (or subproject) and a @.ipr@
that you can directly open for the root project.  To allow IntelliJ Idea to
resolve external dependencies properly, you will need to add a @M2_REPO@
variable pointing to your Maven2 repository directory (@Settings / Path
Variables@).

If you're using IDEA 7 or later, use the @buildr idea7x@ task instead.  This
task creates the proper @.ipr@ and @.iml@ files for IDEA version 7.  It
includes the @-7x@ suffix in the generated files, so you can use the @idea@ and
@idea7x@ tasks side by side on the same project.

Also, check out the "Buildr plugin for
IDEA":http://www.digitalsanctum.com/buildr-plug-in/ (IDEA 7 and later).  Once
installed, open your project with IDEA.  If IDEA finds that you have Buildr
installed and finds a buildfile in the project's directory, it will show all
the tasks available for that project.  To run a task, double-click it.  When
the task completes, IDEA will show the results in the Buildr Output window.


h2. Cobertura, JDepend

You can use "Cobertura":http://cobertura.sourceforge.net/ to instrument your
code, run the tests and create a test coverage report in either HTML or XML
format.

There are two tasks, both of which generate a test coverage report in the
@reports/cobertura@ directory.  For example:

{{{!sh
$ buildr test cobertura:html
}}}

As you can guess, the other task is @cobertura:xml@.

If you want to generate cobertura reports only for a specific project, you
can do so by using the project name as prefix to cobertura tasks. 

{{{!sh
$ buildr subModule:cobertura:html
}}}

Each project can specify which classes to include or exclude from cobertura
instrumentation by giving a class-name regexp to the @cobertura.include@ or 
@cobertura.exclude@ methods:

{{{!ruby
define 'someModule' do 
  cobertura.include 'some.package.*'
  cobertura.include /some.(foo|bar).*/
  cobertura.exclude 'some.foo.util.SimpleUtil'
  cobertura.exclude /*.Const(ants)?/i
end
}}}

You can use "JDepend":http://clarkware.com/software/JDepend.html on to
generate design quality metrics.  There are three tasks this time, the eye
candy one:

{{{!sh
$ buildr jdepend:swing
}}}

The other two tasks are @jdepend:text@ and @jdepend:xml@.

We want Buildr to load fast, and not everyone cares for these tasks, so we
don't include them by default.  If you want to use either one, you need to
require it explicitly.  The proper way to do it in Ruby:

{{{!ruby
require 'buildr/cobertura'
require 'buildr/jdepend'
}}}

You may want to add those to the Buildfile.  Alternatively, you can use these
tasks for all your projects without modifying the Buildfile.  One convenient
method is to add these two likes to the @buildr.rb@ file in your home
directory.

Another option is to require it from the command line (@--require@ or @-r@),
for example:

{{{!sh
$ buildr --require buildr/jdepend jdepend:swing
$ buildr -rbuildr/cobertura cobertura:html
}}}


h2. Anything Ruby Can Do

Buildr is Ruby code.  That's an implementation detail for some, but a useful
features for others.  You can use Ruby to keep your build scripts simple and
DRY, tackle ad hoc tasks and write reusable features without the complexity of
"plugins".

We already showed you one example where Ruby could help.  You can use Ruby to
manage dependency by setting constants and reusing them, grouping related
dependencies into arrays and structures.

You can use Ruby to perform ad hoc tasks.  For example, Buildr doesn't have
any pre-canned task for setting file permissions.  But Ruby has a method for
that, so it's just a matter of writing a task:

{{{!ruby
bins = file('target/bin'=>FileList[_('src/main/dist/bin/*')]) do |task|
  mkpath task.name
  cp task.prerequisites, task.name
  chmod 0755, FileList[task.name + '/*.sh'], :verbose=>false
end
}}}

You can use functions to keep your code simple.  For example, in the ODE
project we create two binary distributions, both of which contain a common set
of files, and one additional file unique to each distribution.  We use a
method to define the common distribution:

{{{!ruby
def distro(project, id)
  project.package(:zip, :id=>id).path("#{id}-#{version}").tap do |zip|
    zip.include meta_inf + ['RELEASE_NOTES', 'README'].map { |f| path_to(f) }
    zip.path('examples').include project.path_to(:source, :examples), :as=>'.'
    zip.merge project('ode:tools-bin').package(:zip)
    zip.path('lib').include artifacts(COMMONS.logging, COMMONS.codec,
      COMMONS.httpclient, COMMONS.pool, COMMONS.collections, JAXEN, SAXON,
      LOG4J, WSDL4J, XALAN, XERCES)
    project('ode').projects('utils', 'tools', 'bpel-compiler', 'bpel-api',
      'bpel-obj', 'bpel-schemas').map(&:packages).flatten.each do |pkg|
        zip.include(pkg.to_s, :as=>"#{pkg.id}.#{pkg.type}", :path=>'lib')
      end
    yield zip
  end
end
}}}

And then use it in the project definition:

{{{!ruby
define 'distro-axis2' do
  parent.distro(self, "#{parent.id}-war") { |zip|
    zip.include project('ode:axis2-war').package(:war), :as=>'ode.war' }
end
}}}

Ruby's functional style and blocks make some task extremely easy.  For
example, let's say we wanted to count how many source files we have, and total
number of lines:

{{{!ruby
sources = projects.map { |prj| prj.compile.sources.
  map { |src| FileList["#{src}/**/*.java"] } }.flatten
puts "There are #{source.size} source files"
lines = sources.inject(0) { |lines, src| lines += File.readlines(src).size }
puts "That contain #{lines} lines"
}}}