Question

About the following code:

if a == 1
  return "a is one"
end

When I execute it inside IRB, it gives me

LocalJumpError: unexpected return

But when I put the same code in my Rails application, it runs flawlessly.

Do I really have to avoid returning explicit values from inside blocks? Why does the Rails application have no problems with it?

Answer 1

When you run this code on its own in the console there is no scope to return from. As soon as it is put inside a method it will work as expected.

Example without scope:

irb(main):001:0> if a = 1
irb(main):002:1>   return "a is one"
irb(main):003:1> end
LocalJumpError: unexpected return
  from (irb):2
  from /Users/dougal/.rbenv/versions/1.9.3-p194/bin/irb:12:in `<main>'

Example scoped inside a method:

irb(main):001:0> def run
irb(main):002:1> if a = 1
irb(main):003:2>   return "a is one"
irb(main):004:2> end
irb(main):005:1> end
=> nil
irb(main):006:0> puts run
a is one
=> nil