On Monday, 12 March 2018 at 03:50:42 UTC, Joe wrote:
On Monday, 12 March 2018 at 03:13:08 UTC, Seb wrote:
Out of interest: I wonder what's your usecase for using qsort.
Or in other words: why you can't use the high-level
std.algorithm.sorting.sort?
This is only temporary. I will be using
std.algorithm.sorting.sort. I was converting a C program and it
annoyed me that I couldn't get the qsort invocation past the D
compiler.
Now that I'm trying to use std.algorithm.sorting, I'm again
puzzled by what I need to use for the "less" predicate. My first
try was:
sort!((a, b) => to!string((*a).name) <
to!string((*b).name))(recs);
This results in the error:
Error: template std.algorithm.sorting.sort cannot deduce function
from argument types !((a, b) => to!string((*a).name) <
to!string((*b).name))(Record*[10]), candidates are:
/usr/lib/ldc/x86_64-linux-gnu/include/d/std/algorithm/sorting.d(1851): std.algorithm.sorting.sort(alias less = "a <
b", SwapStrategy ss = SwapStrategy.unstable, Range)(Range r) if ((ss == SwapStrategy.unstable &&
(hasSwappableElements!Range || hasAssignableElements!Range) || ss != SwapStrategy.unstable && hasAssignableElements!Range)
&& isRandomAccessRange!Range && hasSlicing!Range && hasLength!Range)
which is not very helpful. It's a bit different from the "no
function match" that Adam complains about, but I presume it's
because now we're dealing with templates, and although the
compiler finds a single candidate, it's not satisfactory but it
can't tell the user anything further.
I've tried using fromStringz((*x).name.ptr) instead of to!string
(I'm still unclear to what extent can templates be used within
templates). I also tried using an explicit cast(Record *)x
because I'm also unsure that type information is passed down.
Neither change helped.
