Leveraging the Ruby language for code readability

Recently, I created a rake task to load dummy data into a Rails app. I wanted the data to be somewhat random to make it easier to spot design issues depending on data being filled in or left blank. But at the same time, I want to keep my code as readable as possible.

The idea

If I wanted a certain field to be filled in for one in five instances, I thought it would be quite readable to have code like this

  
  
    with_probability '4 in 5' do
  person.source = ['Walk in', 'Event', 'Word fo mouth', 'Website'].sample
end
  
  

The implementation

All I needed to do was write a simple method leveraging Ruby’s block concept:

  
  
    def with_probability(string, &block)
  string =~ /^(\d+) in (\d+)$/
  probability = $1.to_i
  total = $2.to_i
    
  result = rand(total) < probability

  if block_given?
    yield if result
  else
    result
  end
end
  
  

Simple enough: we pick a random number, and if it fits our criteria, we execute the block. You'll notice I actually test for the block, because I also wanted to be able to use the method without a block:

  
  
    
    person.source = 'Phone call' if with_probability '1 in 3'
  
    
  

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