[swift-users] Dictionary with optional values

David Sweeris davesweeris at mac.com
Wed May 18 20:58:00 CDT 2016

This isn't limited to Optional. Any dictionary whose value type conforms to NilLiteralConvertible can be "vulnerable" to some pretty subtle bugs.

- Dave Sweeris

> On May 18, 2016, at 13:16, Jens Alfke via swift-users <swift-users at swift.org> wrote:
> (Thinking about it, I can’t see much use for a dictionary of optionals. What’s the difference between “x has no value” and “x has a value of nil”? I guess it’s that when you iterate the keys you see x. This seems like a tricky use that could easily confuse someone reading the code (who could be you, a year later!) Personally I’d prefer a different, clearer solution, unless this was something performance-critical that led to faster code. In which case I’d add lots of comments!)
> —Jens
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