yields and blocks in Rails

rubyonrails-talk
1

The below code works just fine in Ruby but I get a LocalJumpError in Rails stating "no block given". I thought I knew what a block was, but given the results, I am not so sure. Could someone please offer an explanation as to what is going on?

Thanks, C.

class Array   def comb(n = size)     if size < n or n < 0     elsif n == 0       yield()     else       self[1..-1].comb(n) do |x|         yield(x)       end       self[1..-1].comb(n - 1) do |x|         yield([first] + x)       end     end   end end

2

HI --

3

I was trying to run it in some controller code. I gave up trying to do anything fancy and just focused on getting something simple to run. The exception name in the header is LocalJumpError, and the error message in the box is "no block given". I placed the array extension as the first thing in the controller file before the controller class. I call the sample below from within a method in the controller class.

['a','b','c','d'].comb(3).each do |element|     puts element end

here is where it points to the errors: app/controllers/courses_controller.rb:11:in `comb' app/controllers/courses_controller.rb:11:in `comb' app/controllers/courses_controller.rb:5:in `comb' app/controllers/courses_controller.rb:10:in `comb'

Because it is the first thing in the file, the line numbers will add up with the previous code example. They point to the yields.

thanks, C.

4

Charles wrote:

['a','b','c','d'].comb(3).each do |element|     puts element end

You should get a LocalJumpError with this code in Ruby, too. Remove the ".each" and it should be ok.

5

Thanks for the eyes :slight_smile: with the array output, i was tacking on a .each without even thinking about it. Comparing the ruby code, i completely glossed over the .each .

I appreciate it!

C.