precedence: A Ruby repository from farrel

= Precedence

Precedence is a library that allows for the creation, manipulation and analysis
of precedence networks.

== Download and Install

Available as a RubyGem from Rubyforge. To install
 $ gem install precedence
will fetch the latest gem from Rubyforge and install it.

Source can also be downloaded from  http://rubyforge.org/projects/precedence.

== Example Usage
 require('precedence')
 
 # Set up network
 net = Precedence::Network.new('Begin','End')
 net.new_activity('act-1-1') do |act|
 	act.duration = 3
 	act.description = 'System specification'
 end
 net.new_activity('act-1-2' do |act|
 	act.duratiom = 2
 	act.description = 'Review'
 end
 net.new_activity('act-1-3') do |act|
 	act.duration = 2
 	act.description = 'System re-specification'
 end
 net.new_activity('act-2-1') do |act|
 	act.duration = 3
 	act.description = 'Test tool design'
 end
 net.new_activity('act-2-2') do |act| 
 	act.duration = 5
 	act.description = 'Test tool implementation'
 end
 net.new_activity('act-3-1')
 	act.duration = 3
 	act.description = 'System design'
 end
 net.new_activity('act-3-2') do |act|
 	act.duration = 12
 	act.description = 'System implementation'
 end
 net.new_activity('act-2-3') do |act| 
 	act.duration = 10
 	act.description = 'System testing'
 end
 net.connect('act-1-1','act-1-2')
 net.connect('act-1-2','act-1-3')
 net.connect('act-1-3','act-3-1')
 net.connect('act-1-2','act-2-1')
 net.connect('act-2-1','act-2-2')
 net.connect('act-2-2','act-3-2')
 net.connect('act-3-1','act-3-2')
 net.connect('act-3-2','act-2-3')
 net.fix_connections!
 
 # Generate a diagram
 File.open('network.dot',File::CREAT|File::TRUNC|File::WRONLY) do |file|
	file.puts(net.to_dot)
 end
 system("dot","-Tpng","-onetwork.png","network.dot")
 
 # Perform some analysis of the activities
 activity = net.activities['act-1-2']
 activity.on_critical_path? # => true 
 activity.earliest_start # => 3.0
 activity.latest_finish # => 5.0
 activity.total_float  # => 0 - activities on the critical path have no float
 
 # Save the network to a YAML file
 File.open('network.yaml',File::CREAT|File::TRUNC|File::WRONLY do |file|
 	file.puts(net.to_yaml)
 end
 
 # Read the network from a YAML file
 newNet = Precedence::Network.from_yaml(File.new('network.yaml',File::RDONLY))
 
== Documentation

The Precedence API online documentation is available at 
http://precedence.rubyforge.org. 

Refer to the CHANGELOG and TODO files for past changes and upcoming plans.

== Credits

Farrel Lifson <farrel@lifson.info>

== License

This software is made available under the BSD license.
farrel/precedence
