ChainIt

Description

This provides the tool which is implementation of railway-oriented programming concept itself (Read more on this here).

Ideally suited for executing task sequences that should be immediately interrupted when any subsequen task fails.

Usage

Everything comes down to chaining subsequent #chain method calls to a ChainIt object instance.

The gem supports design-by-contract programming concept - assuming every block related to #chain have to return both #value and #failure? aware object.We reccomend using Struct for that purpouse.

Result = Struct.new(:success, :value) do
  def failure?
    !success
  end
end

Examples

# Basic flow explanation
success = ->(value) { Result.new(true, value) }

ChainIt.new.
        chain { success.call 2 }.               #=> The subsequent chain will be triggered
        chain { |num| success.call(num * 2) }.  #=> We can pass the previous block evaluation as the block argument
        chain { |num| success.call(num * 2) }.
        result.
        value                                   #=> 8

# Working with #skip_next
ChainIt.new.
        chain { success.call 2 }.               
        skip_next { |num| num == 2 }.           #=> The next chain will be skipped conditionally since block returns true
        chain { success.call 8 }.              
        chain { |num| success.call(num * 2) }.  #=> The block argument is the last executed #chain value
        result.
        value                                   #=> 4

# Dealing with a failure
failure = ->(value) { Result.new(false, value) }

ChainIt.new.
        chain { success.call 2 }.
        chain { failure.call 0 }.               #=> All later #chain calls will be skipped
        chain { success.call 4 }.
        result.
        value                                   #=> 0

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/spark-solutions/chain_it.

License

The gem is available as open source under the terms of the MIT License.