fearless_fool wrote:
> This is more a Ruby than a Rails question -- feel free to redirect me
> as appropriate -- but either this is a Ruby 1.9 bug or I have some
> serious misunderstanding. Essentially, I've caught the <=> operator
> returning nil -- not -1, 0, or 1, but nil. Schematically:
>
> class A
> attr_accessor :slot
> fun matches?(s)
> p "s <=> @slot = #{s <=> @slot}"
> return (s <=> @slot) == 0
> end
> end
>
> Driven from a script, I get something like this:
>
> # Case 1: Notice that <=> evaluates to nil when it should eval to 0
> a.slot = "dog"
> a.matches?("dog")
> "s <=> @slot = "
> => false
>
> # Case 2: When I pass a String.new("dog") everything works
> a.slot = "dog"
> a.matches?(String.new("dog"))
> "s <=> @slot = 0"
> => true
>
> What's really odd is that called interactively, Case 1 works as
> expected. When called from a script, it exhibits the oddity above.
>
> Am I missing something fundamental about Ruby and string comparison?
>
> - ff
Can't reproduce with what you've given.
ruby-1.9.1-p376 > class A
ruby-1.9.1-p376 ?> attr_accessor :slot
ruby-1.9.1-p376 ?> def matches? s
ruby-1.9.1-p376 ?> puts "s <=> @slot = #{s <=> @slot}"
ruby-1.9.1-p376 ?> (s <=> @slot) == 0
ruby-1.9.1-p376 ?> end
ruby-1.9.1-p376 ?> end
=> nil
ruby-1.9.1-p376 > a = A.new
=> #<A:0x000000041915b8>
ruby-1.9.1-p376 > a.slot = "dog"
=> "dog"
ruby-1.9.1-p376 > a.matches? "dog"
s <=> @slot = 0
=> true
ruby-1.9.1-p376 >
String comparison via <=> to nil will return nil. Are you entirely sure
that in your IRB session your object's @slot isn't nil for some reason?
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