On Tuesday, 22 April 2014 at 18:17:58 UTC, Ali Çehreli wrote:
On 04/22/2014 11:03 AM, monarch_dodra wrote:
> The "int[] reduce...", however, I think is a outright
language issue.
> Implicilty calling opSlice on a static array is one thing,
but doing it
> on an rvalue is an outright aberration. The code should be
rejected no
> questions asked.
I don't think there is slicing an rvalue though. (?) reduce()
is taking a copy of the seed and then returning a slice to it
because the user slices it in their lambda. It effectively does
the following, which unfortunately compiles:
int[] foo()
{
int[1] sum;
return sum[]; // <-- no warning
}
Reduce returns "the seed". It's actually doing something more
like this:
int[1] foo()
{
int[1] sum
sum = sum[]; //The lambda operates, and the
//result is assigned back to the seed.
return sum; //Returns the seed.
}
So when writing:
void main()
{
int[] result = foo();
}
There's a *second* level of bug. (assigning an rvalue "int[1]" to
int[])
*This* works fine though:
int[1] seed;
int[1] result = reduce!((ref sum, _) => sum)(seed, arr);
BTW, I'm re-implemented reduce recently (not yet pulled), but I
was *very* thorough about documenting what it does:
https://github.com/D-Programming-Language/phobos/pull/2060
Could you take a look at it (the documentation I mean), and tell
me if everything is what you would have expected?
