Conditional key/value in a ruby hash

Question

Is there a nice (one line) way of writing a hash in ruby with some entry only there if a condition is fulfilled? I thought of

{:a => \'a\', :b => (\'b\         


        

Answer 1

Hash[:a, 'a', *([:b, 'b'] if condition1), *([:c, 'c'] if condition2)]

This relies on the fact that *nil expands to vacuity in ruby 1.9. In ruby 1.8, you might need to do:

Hash[:a, 'a', *(condition1 ? [:b, 'b'] : []), *(condition2 ? [:c, 'c'] : [])]

or

Hash[:a, 'a', *([:b, 'b'] if condition1).to_a, *([:c, 'c'] if condition2).to_a]