On Wednesday, 5 November 2014 at 16:54:38 UTC, Marc Schütz wrote:
On Wednesday, 5 November 2014 at 16:07:40 UTC, Nordlöw wrote:
On Wednesday, 5 November 2014 at 14:36:11 UTC, Marc Schütz
wrote:
It's intuitive and concise. Plus, Ruby uses `sort` and
`sort_by` for the same functionality, exactly in parallel, so
it will be familiar to many users.
Here's my first working but primitive version.
https://github.com/nordlow/justd/blob/master/sort_ex.d#L15
How do I extend it to support
- variadic number of extractors
- sortBy("x")
My idea was something along these lines (untested):
template extractorFun(alias extractor) {
static if(is(typeof(extractor) : string)) {
auto ref extractorFun(T)(auto ref T a) {
mixin("with(a) { return " ~ extractor ~ "; }");
}
} else {
alias extractorFun = extractor;
}
}
alias fn = extractorFun!extractor;
r.sort!((a, b) => (fn(a) < fn(b)));
Works! Thanks!
One thing: I tried to add support for integer based member
indexing via tupleof at
https://github.com/nordlow/justd/blob/master/sort_ex.d#L21
but it errors as
sort_ex.d(42,46): Error: function expected before (), not 0 of
type int
sort_ex.d(43,46): Error: function expected before (), not 0 of
type int
sort_ex.d(42,6): instantiated from here: sort!((a, b) =>
extractorFun!extractor(a) < extractorFun!extractor(b),
cast(SwapStrategy)0, X[])
sort_ex.d(80,6): instantiated from here: sortBy!(0, X[])
/home/per/opt/x86_64-unknown-linux-gnu/dmd/linux/bin64/src/phobos/std/algorithm.d(10266,9):
Error: static assert "Invalid predicate passed to sort:
__lambda2"
sort_ex.d(42,6): instantiated from here: sort!((a, b) =>
extractorFun!extractor(a) < extractorFun!extractor(b),
cast(SwapStrategy)0, X[])
sort_ex.d(80,6): instantiated from here: sortBy!(0, X[])
when I uncomment the last three tests. What's wrong?
