Passing multiple code blocks as arguments in Ruby

ruby yield

doctororange · Mar 17, 2010 · Viewed 16k times · Source

I have a method which takes a code block.

def opportunity
  @opportunities += 1
  if yield
    @performances +=1
  end
end

and I call it like this:

opportunity { @some_array.empty? }

But how do I pass it more than one code block so that I could use yield twice, something like this:

def opportunity
  if yield_1
    @opportunities += 1
  end
  if yield_2
    @performances +=1
  end
end

and:

opportunity {@some_other_array.empty?} { @some_array.empty? }

I am aware that this example could be done without yield, but it's just to illustrate.

Answer

You can't pass multiple blocks, per se, but you can pass multiple procs or lambdas:

Using 1.9 syntax:

opportunity ->{ @some_array.empty? }, ->{ @some_other_array.empty? }

and in the method itself:

def opportunity(lambda1, lambda2)
  if lambda1.()
    @opportunities += 1
  end
  if lambda2.()
    @performances += 1
  end
end