Feature request: ssize_t, a signed size_t

[Julio César Carrascal Urquijo]

I was writing something like the following code:

// double y1, y2, width;
size_t index = to!size_t((x2 - x1) / width);
if (index >= 0 && index < grid.length) {
     ...
} else {
     ...
}

When I finished writing the condition I remembered that size_t is 
actually an uint so it can't be negative.

Just for fun I tested this:

writeln(to!size_t(-1));

std.conv.ConvOverflowException at std\conv.d(8): Error: overflow Conversion 
negative overflow

That's not what I was expecting but it's OK. For my use case I changed 
the code use int but, with 64bit already here, that's not quite correct.

So if I may suggest: Could we have a signed size_t in Phobos? ssize_t or 
with another name.

I don't want to replace size_t. I just want a signed type that's correct 
for storing an index for an array in 32 and 64 bit.

PS: I realize this has been discussed before. I just hope we get some 
luck this time. <g>

Thanks