BitStruct

Its main use is in defining network protocol packets used for network protocols (IP).

Installation:

For .gem: Run the command gem install bit-struct
For .tgz, unpack and run these commands:
  ruby install.rb config
  ruby install.rb setup
  ruby install.rb install

Features:

• Extensible with user-defined field classes.
• Fields are fully introspectable and can be defined programmatically.
• BitStruct.describe prints out documentation of all the fields of a BitStruct subclass, based on declarations. This is useful for communicating with developers who are not using ruby, but need to talk the same protocols.
• Fields are inherited by subclasses.
• BitStruct#inspect and BitStruct#inspect_detailed can be used for prettified display of contents.
• BitStruct inherits from String, so all the usual methods are available, and string-sharing (copy-on-write) is in effect.
• Easy access to a "prototype" instance of each BitStruct subclass, from which all instances of that subclass are initialized as a copy (in the absence of other initialization parameters, such as a hash, a string, or a block). See BitStruct.initial_value, and BitStruct#initialize.
• Easy conversion to and from hashes, using BitStruct#to_h and BitStruct.new.
• BitStructs can persist using Marshal (a BitStruct is after all just a string) or using YAML (with human readable representation of the fields).
• Includes tests, examples, and rdoc API documentation.

What is new in this release:

• Modernize rakefile and gemspec.
• Switch to minitest.

What is new in version 0.13.4:

• Packaged as a gem using bones.
• Added nest fields defined with blocks.
• Vector length may be specified as argument or :length option.

Limitations:

• Fields that are not aligned on byte boundaries may cross no more than two bytes boundaries.
• No variable length fields (except the rest field).