> On Dec 5, 2017, at 1:13 PM, Thorsten Seitz via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> let result = dynamic x.foo.bar // will crash if foo or bar are not present
>
> let result = dynamic? x.foo.bar // will return nil if foo or bar are not
> present
>
> // will crash if foo or bar are not present
> let result = dynamic {
> let y = x.foo.bar
> let z = y.baz(42)
> return z.zork()
> }
>
> // will return nil if foo or bar are not present
> let result = dynamic? {
> let y = x.foo.bar
> let z = y.baz(42)
> return z.zork()
> }
As other people have pointed out, the behavior of something conforming to these
protocols in no way implies that they crash if lookup fails. That is up to the
implementer, and I assume most, if not all, will choose sane defaults
(optional/throws) rather than just crashing.
But I think the main thing missing from this is where `x` came from. As I think
Chris pointed out before, these values have to come from somewhere. If you have
no idea what the type of the variable you're dealing with is and what its
intended behavior might be, then I don't understand how you could even write
this code in the first place.
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