I don’t think that solves the same thing. The problem is I read it is to allow some sort of short hand to be able to pass optional types as parameters into methods / initializers that do not take optional types. The result of that method / initializer being nil if any of said parameters were nil or a typical result otherwise. Based on your example I think it’s identical to the existing ?? operator, is it not?
As per the suggested syntax, I do think that we would want to be able to control this feature on a per parameter basis, so it would make sense to have the ? operator placed after the parameter that needed to be unwrapped. This would also be more consistent with the usage of the existing syntax. — Charles > On Dec 11, 2017, at 9:37 AM, C. Keith Ray via swift-evolution > <swift-evolution@swift.org> wrote: > > You can create a binary operator that tests the left-hand operand for nil, > and passes the unwrapped value to the right-hand operand (a function taking > one value), this operator can be made left-associative to allow chaining. > > let m = String(contentsOfFile: "README.md") ??? Markdown > where ??? is the operator described above. > > -- > C. Keith Ray > > * https://leanpub.com/wepntk <https://leanpub.com/wepntk> <- buy my book? > * http://www.thirdfoundationsw.com/keith_ray_resume_2014_long.pdf > <http://www.thirdfoundationsw.com/keith_ray_resume_2014_long.pdf> > * http://agilesolutionspace.blogspot.com/ > <http://agilesolutionspace.blogspot.com/> > > On Dec 11, 2017, at 9:07 AM, Magnus Ahltorp via swift-evolution > <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote: > >> >>> 12 Dec. 2017 01:30 Jared Khan via swift-evolution >>> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote: >>> >>> I'd like to propose a syntax addition that acts to ease some things that I >>> believe should fall under the umbrella of 'optional chaining'. Optional >>> chaining allows us to access the properties of an optional value and return >>> nil if any link in that chain breaks. I propose we introduce syntax to >>> allow similar chaining when passing optional valued parameters to functions >>> that expect that parameter to be non-optional. >> >> 1. Am I right in assuming that you propose that the suffix operator "?" >> would make the result of the surrounding method/function call optional, so >> that a(b(c?)) would make the result of the "b" function call optional, but >> not the "a" function call, and that it would be a(b(c?)?) if we would like >> to propagate this two levels? >> >> 2. If that is the case, is that understandable/neat enough? How common would >> you expect this to be? >> >> 3. For some reason, (in current Swift) the suffix operator "?" seems to be >> allowed in intra-expression syntax, and only fails when the inter-expression >> syntax is checked for optionality congruence. Is there a reason for this? I >> would have expected that the congruence error "cannot use optional chaining >> on non-optional value of type" would never be seen for a lone "?", since the >> error message "'?' must be followed by a call, member lookup, or subscript" >> would always be displayed first if it was checked first. The "." operator >> checks intra-expression syntax first, before checking congruence. Is this a >> sign that "?" as a suffix operator is already somewhat operational as an >> operator for optional types? I have a faint recollection that it was doing >> something in earlier versions of Swift. >> >> /Magnus >> >> _______________________________________________ >> swift-evolution mailing list >> swift-evolution@swift.org <mailto:swift-evolution@swift.org> >> https://lists.swift.org/mailman/listinfo/swift-evolution >> <https://lists.swift.org/mailman/listinfo/swift-evolution> > _______________________________________________ > swift-evolution mailing list > swift-evolution@swift.org > https://lists.swift.org/mailman/listinfo/swift-evolution
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