My original intention was to get rid of re-defining what should be the sequence
sorted by. For example, if self.sorted { $0.age < $1.age } was at 10 places in
code, I would not consider it a good coding technique and would definitely
suggest the person to create a method for this - sortedByAge().
self.sorted(.ascending) { $0.age } is a bit better, but I still feel that there
is a lot of duplicate code and if one used this in 10 places over the project,
a method for this should be created instead.
Don't you agree that people.sortedByAge() reads better than
self.sorted(.ascending) { $0.age }?
What I was also aiming at is possibly something that could replace e.g.
NSSortDescriptor, which can be handy in the UI, but requires dynamic (@objc)
properties in order to work.
What I'm suggesting, would also emit a function symbol for sorting the array by
a particular key, so the sorting could actually be dynamic - supply a key
(using #keyPath()) which is @sortable, given name mangling is stable in Swift
4, you can create the well-defined function symbol name, make a lookup via dyld
and call it.
Note that the NSSortDescriptor is just an example and given most of my
development is on macOS, I use bindings and NSArrayController where the sort
descriptors are fairly common unlike with iOS... But the usage of this can be
extended to many other areas given that you *know* that there is a function out
there, with that particular signature that will sort the array...
> On Aug 17, 2016, at 12:45 AM, Xiaodi Wu <[email protected]> wrote:
>
> On Tue, Aug 16, 2016 at 5:35 PM, Anton Zhilin <[email protected]
> <mailto:[email protected]>> wrote:
> What we need here is sort_by from Ruby. How about adding these overloads?
>
> func sort<U: Comparable>(by: (T) -> U)
> func sorted<U: Comparable>(by: (T) -> U) -> [T]
>
> I'd be in favor. We'd need another name, since the current closure predicate
> is already standardized to `by:`.
> (Or, as I propose above, once `Ordering` comes to the stdlib, we can just
> have it as `func sort<U: Comparable>(_ ordering: Ordering, by: (T) -> U)`,
> called like `sort(.ascending) { $0.age }`.)
>
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