> On Dec 19, 2015, at 9:21 AM, Tino Heth via swift-evolution > <swift-evolution@swift.org> wrote: > > Hi there, > > this idea might be quite unconventional, but it is simple and wouldn't break > any existing code. > Returning void has no use beside telling "there is nothing to return" and > makes it impossible to perform method chaining, which drives popular systems > like iostream and LINQ (the concept was promoted by Martin Fowler as fluent > interface - but wikipedia has a good explanation on this: > https://en.wikipedia.org/wiki/Fluent_interface > <https://en.wikipedia.org/wiki/Fluent_interface>) > One of its most popular use cases is database access, which imho will become > quite important for Swift as it might gain popularity in the server domain. > It is useful in other areas as well, but I'll stick to databases in an > example: > > let kids = userDatabase.select(.name).where(.age < 18) > > This is already possible in Swift today, but with a simple change, it could > be much more fun: > I guess void is the natural choice for a default return value - what else is > guaranteed to exist in a function? > For methods, on the other hand, there is a real object that is always > available: self. > If self would be the default return value, we would get method chaining for > free in all places where we now stuck with void - and whoever doesn't like > the concept can still ignore the value as he did with (). > > I have to admit that right now there is a proposal that wants to sanction > ignoring non-void return values with warnings, which would interfere with > this idea; but imho even in this case the workarounds wouldn't be that > complicated. > > So, please give feedback wether it is worth the burden of writing a official > proposal or start by creating a library with the current toolset and try to > prove the usefulness of fluent interfaces ;-)
In order to evaluate this more fully, I'd like to see some examples of real code that would be improved by having this facility, but in general, I'd be concerned that this proposal making mutating/side-effectful method calls look more like purely-functional ones. -Dave
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