[ruby-core:71166] Re: [Ruby trunk - Feature #11537] Introduce "Safe navigation operator"

[Matthew Kerwin <matthew@kerwin.net.au>]

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On 23/10/2015 2:46 AM, <merch-redmine@jeremyevans.net> wrote:
>
> Issue #11537 has been updated by Jeremy Evans.
>
>
> Tom Reznick wrote:
> > Hi,
> >
> > I think we may have found some unexpected behavior with the `.?`
operator.
> >
> > If I call the following:
> >
> >     s = Struct.new(:x)
> >     o = s.new()
> >     o.x #=> nil
> >     o.x.nil? #=> true
> >     o.x.?nil? #=> nil
> >     o.x.kind_of?(NilClass) #=> true
> >     o.x.?kind_of?(NilClass) #=> nil
> >     o.x.methods.include?(:nil?) #=> true
> >
> >
> > While it's arguably a bit peculiar to try to check that `nil` is `nil`,
in a `nil`-safe way, `.?kind_of?(NilClass)` could reasonably return `true`.
>
> I think it's completely expected that `nil.?kind_of?(NilClass)` returns
`nil` and not `true`.  The whole point of `.?` is to return `nil` without
calling the method if the receiver is `nil`.  I'm not sure if `.?` is a
good idea syntax-wise, but if you are going to have it, it shouldn't have
special cases for specific methods.
>

I agree, or put another way: if you're testing for nil in two ways, .? has
higher priority. That makes it a programmer issue, not a ruby one.

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