Mtransform

version 0.0.1

About

Mtransform is a dsl for manipulating keys and values of Hashes. The keys should be symbols.

Installation

Add gem 'mtransform', github: 'egwspiti/mtransform' to your Gemfile.

Usage

There are 3 ways to use this dsl:

• Directly use Mtransform::transform passing it the hash to be manipulated and a DSL block:

  require 'mtransform'
  
  z = Mtransform::transform(a: 3, b: -2, c: 'xxx', d: '') do
    as_is :f, :g
    rename :a => :aa
    set :z => 'Hello'
    set :b do |input, _|
      input[:b] > 0 ? 'positive' : 'negative'
    end
    set :a do |input, _|
      input[:a] * input[:b]
    end
    set(:w) { |_, output| output[:a] * 25 }
  end
  

• Include Mtransform in a class and then use the provided transform method passing it the hash to be manipulated and a dsl block:

  require 'mtransform'
  
  class MyTransform
    include Mtransform
  
    def multiply(a, b)
      a * b
    end
  
    def formula(a)
      a * 25
    end
  
    def run(input)
      transform(input) do
        as_is :f, :g
        rename :a => :aa
        set :z => 'Hello'
        set :b do |input, _|
          input[:b] > 0 ? 'positive' : 'negative'
        end
        set :a do |input, _|
          multiply(input[:a], input[:b])
        end
        set(:w) { |_, output| formula(output[:a]) }
      end
    end
  end
  
  z = MyTransform.new.run(a: 3, b: -2, c: 'xxx', d: '')
  

• Create an Mtransform::Transformer object passing it the DSL block and then invoke transform on it passing it the hash to be manipulated:

  require 'mtransform'
  
  transformer = Mtransform::Transformer.new do
    as_is :f, :g
    rename :a => :aa
    set :z => 'Hello'
    set :b do |input, _|
      input[:b] > 0 ? 'positive' : 'negative'
    end
    set :a do |input, _|
      input[:a] * input[:b]
    end
    set(:w) { |_, output| output[:a] * 25 }
  end
  
  z = transformer.transform(a: 3, b: -2, c: 'xxx', d: '')
  

DSL Commands

as_is

Specify which keys should appear in the output hash without any modification of either the key or its value.

rename

Specify keys to be renamed in the output hash. Only the keys are renamed. It accepts a hash argument whose keys are the inputs keys and values are the desired output keys.

set

set command has two forms, one accepting a hash argument and another one accepting a symbol argument and a block:

• Hash argument

The key of the hash refers to a key into the output hash, while the value of hash is the desired value for that key.

• Symbol argument and block

The symbol refers to a key into the output hash. The value of that key will be the value returned by the evaluation of the supplied block.

rest

By default, all the keys that aren't set by the dsl are discarded. Pass :keep to rest in order to copy them into the output hash.

Contributing

1. Fork it ( http://github.com/egwspiti/mtransform/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request