On Monday, 19 August 2013 at 21:03:50 UTC, Andrei Alexandrescu
wrote:
I'm saying that there's a mix of useful stuff and just
syntactic additions that are arguably less so. In my opinion:
a) destructuring tuples in auto declarations - good to have:
auto (a, b, c) =
functionReturningTupleOrStaticArrayWith3Elements();
b) syntactic support for ignoring certain members in a
destructuring - is that really needed?
auto (a, ?, c) =
functionReturningTupleOrStaticArrayWith3Elements();
In fairness, it is very common in other languages with pattern
matching/destructuring. Off the top of my head I can think of
Haskell, ML, Racket, Javascript (destructuring only) and Rust.
This syntax is more important when pattern matching, but also
seems to be almost universally used in destructuring. From the
DIP:
switch (tup) {
case {1, 2}:
case {$, 2}: //Don't care what the first value is, only match
on second
case {1, x}:
default:
}
You could just replace {$, 2} with {x, 2} and never use x, but
this creates the problem that Bearophile mentioned.
auto t1 = #(5, "hello", 1.5); //Fine
auto #(_, _, x) = t1; //Dammit, can't use _ twice as it's a
variable
If you replace _ with throwaway variable names, it becomes much
less clear (IMO) exactly what is going on. Any programmer reading
your code would have to examine the function to see if the
bindings introduced are ever used, or if they are just throwaways.
Maybe it's unproductive to argue over the colour of the bike
shed, but we need to know whether it's worth adding windows.
