Unexpected return error in Ruby

Question

I'm new to learning Ruby and am having a little trouble with nested structures.

What I'm trying to do is return :last name ("Doe") if the value of :first is "John":

people = {
  :family => [
    {:first => "John", :last => "Doe"},
    {:first => "Jane", :last => "Smith"}
  ]
}

people[:family].each {|index| return index[:last] if index[:first] == "John"}

However, the console is giving me this error:

test.rb:8:in `block in <main>': unexpected return (LocalJumpError)
from test.rb:8:in `each'
from test.rb:8:in `<main>'

When I test this in the console and replace 'return' with 'puts', it gives me back "Doe" but for some reason the 'return' seems to be causing the 'unexpected return (LocalJumpError)'. How can I successfully return this value without running into this error?

Thanks - any and all help is greatly appreciated!

You're returning inside the `.each`, which isn't the same as returning from a method (hence, unexpected). You want [`.select{}`](http://ruby-doc.org/core-2.2.1/Enumerable.html#method-i-select) — Jon Egeland, Mar 07 '15 at 17:04

Anton Harniakou · Answer 1 · 2015-03-07T17:44:51.060

1

Use break with value

people = {
  :family => [
    {:first => "John", :last => "Doe"},
    {:first => "Jane", :last => "Smith"}
  ]
}

people[:family].each {|index| break index[:last] if index[:first] == "John"}

edited Mar 07 '15 at 17:44

answered Mar 07 '15 at 17:22

Anton Harniakou

855
6
13

score 1 · Accepted Answer · answered Mar 07 '15 at 17:23

You can't use return within an each loop. You could use map or collect to return an array of last names like so:

people[:family].collect {|index| index[:last] if index[:first] == "John"}
=> ["Doe", nil]

You could also push your matches to an output variables like so:

output = []
people[:family].each {|index| output << index[:last] if index[:first] == "John"}
=> ["Doe"]

Using break as was suggested, will return a string of the first match, but if you have more than one match, it will not work for you. See example below:

people = {
  :family => [
    {:first => "John", :last => "Doe"},
    {:first => "Jane", :last => "Smith"},
    {:first => "John", :last => "Galt"}
  ]
}
people[:family].each {|index| break index[:last] if index[:first] == "John"}
=> "Doe"

score 0 · Answer 3 · answered Mar 07 '15 at 17:05

0

return needs to be used inside a method:

def foo
  # your code
end

foo # => "Doe"

answered Mar 07 '15 at 17:05

August

12,410
3
35
51

This isn't going to solve the problem. Returning inside the `.each` isn't allowed. See http://stackoverflow.com/questions/2518075/how-can-i-return-something-early-from-a-block – Jon Egeland Mar 07 '15 at 17:07
Maybe you should try it. – August Mar 07 '15 at 17:13
"Not allowed" isn't the right term, but there are better ways to do it. – Jon Egeland Mar 07 '15 at 17:15

score 0 · Answer 4 · answered Mar 07 '15 at 17:27

0

puts people[:family].find({}) {|index| index[:first] == "John"}[:last]

answered Mar 07 '15 at 17:27

Maxim

9,701
5
60
108

Unexpected return error in Ruby

4 Answers4