Question

This completely confused me for a while. I’m getting weird behaviour trying to loop through lines of text in erb, with the whole line of text being printed when the loop is complete.

<% "some\nmultiline\ntext".each_line do |line| %>
  <%= line %> <br />
<% end %>

Outputs:

some 
multiline 
text 
some multiline text

And so does:

<% "some\nmultiline\ntext".lines.each do |line| %>
  <%= line %> <br />
<% end %>

But the following works as I would expect it to:

<% "some\nmultiline\ntext".lines.to_a.each do |line| %>
  <%= line %> <br />
<% end %>

and prints:

some 
multiline 
text 

I’m definitely not just putting in an = accidentally. What could be causing this strange behaviour?

I’m using Rails 3.0.10, Ruby 1.9.2.

Answer 1

I can’t say for sure but "some\nmultiline\ntext".lines is Enumerator and "some\nmultiline\ntext".lines.to_a is Enumerable the big difference is that when you mix in Enumerable module to your class you have to define each method whose job it is to
yield items to a supplied code block, one at a time. Enumerators are a recent and significant addition to Ruby. An enumerator is an object, not a method. An enumerator isn’t a container object. It has no “natural” basis for an each operation, the way an array does (start at element 0; yield it; go to element 1; yield it; and so on). The each iteration logic of every enumerator has to be explicitly specified.