Question

I wrote the following Ruby code:

def myItems
    if @item1
        yield @item1
    end
    if @item2
        yield @item2
    end
end

Now I tried to use:

myItems.each do |item|
    puts item
end

However, when both @item1 and @item2 are nil, I get the error:

Error: #<NoMethodError: undefined method `each' for nil:NilClass>.

I would expect an equivalent to “yield break” in C# to prevent this. Does anyone know how this works in Ruby?

Answer 1

It’s hard to tell what you are trying to do, but I think you want simply:

myItems do |item|
  puts item
end

Your current code is assuming that the return value of myItems is an enumerable (e.g. an array), and under no circumstance (even if your @items are not nil) is that the return value.

Alternatively, do either this:

# Method that iterates over all items
def eachItem
  [@item1,@item2].compact.each do |item|
    yield item
  end
end

eachItem do |item|
  puts item
end

…or this:

# Give me an array of all non-nil items
def myItems
  [@item1,@item2].compact
end

myItems.each do |item|
  puts item
end

Note: I’ve used camelCase method names because that’s what you have originally, but note that it’s idiomatic in Ruby to use snake_case instead.

Note 2: storing multiple similar items as instance variables instead of as a collection seems less useful than storing the collection itself. However, without knowing your data I cannot suggest a better way to represent this.