Question

I find this line in the ZenTest source code:

result = @test_mappings.find { |file_re, ignored| filename =~ file_re } 

The @test_mappings and result here are both Array object, but I didn’t found ‘find’ method on Array class in ruby doc. I also tried it on irb:

irb(main):014:0> Array.respond_to? :find => false irb(main):015:0> [1,2,3].find LocalJumpError: no block given         from (irb):15:in `find'         from (irb):15:in `each'         from (irb):15:in `find'         from (irb):15 irb(main):016:0> [1,2,3].find{|x| x>1} => 2 

Could any one explain it to me? How could find method also return an Array object? thanks in advance.

Answer 1

Array includes the Enumerable module, which adds the find method.

In your example you tested Array.respond_to. This will only return true for class methods of Array. find is an instance method, so respond_to? must be invoked on an instance of the class.

>> a = Array.new => [] >> a.respond_to? :find => true