Ruby Block Variable not defined error in one line, but works on do..end block

Question

I don't know how to explain this more, I'm open to suggestions.

Here is an example:

User.last.orders.detect { |user_order| user_order.query.id == 107 }

This doesn't work;

NameError: undefined local variable or method ` user_order' for main:Object
from (pry):51:in `block in <main>'

But this works:

User.last.orders.detect do |user_order|
  user_order.query.id == 107
end

This is just a simple example. I really don't understand why this happens. Thanks!

As pointed out below, it's likely a whitespace issue with your code. Otherwise, the code looks fine. — Sergio Tulentsev
– Sergio Tulentsev, Commented Oct 31, 2017 at 9:47

Sebastián Palma · Accepted Answer · 2017-10-31 09:43:24Z

2

The problem is you have an additional "non-breaking space" between the pipe and user_order, that's why the message says:

NameError: undefined local variable or method ` user_order' for main:Object

Your actual variable is " user_order" not "user_order".

This commonly happens when pressing alt and space at the same time (on OSX), that's common when opening curly braces for "inline" blocks in Ruby.

edited Oct 31, 2017 at 9:43

answered Oct 31, 2017 at 9:40

Sebastián Palma

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4 Comments

Sergio Tulentsev Over a year ago

"user_order not user_order" - wat? these are the same, no?

Simple Lime Over a year ago

SO strips whitespace it views as un-necessary. Took me a minute to see as well, but if you look at the original error message things become more obvious when you're looking for a leading whitespace char in the variable name

Sergio Tulentsev Over a year ago

@SimpleLime: ah, indeed. Yes, must be some unusual unicode whitespace in the source code.

user1934428 Over a year ago

@SergioTulentsev : In such cases, it helps looking at the code with a hex editor. This helps to identify the culprit.

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