On Sunday, 11 August 2013 at 17:01:46 UTC, Yota wrote:
On Friday, 9 August 2013 at 17:35:18 UTC, monarch_dodra wrote:
On Friday, 9 August 2013 at 15:28:10 UTC, Manfred Nowak wrote:
michaelc37 wrote:
WTF -> -1 is greater than 7 ????
From the docs:
It is an error to have one operand be signed and the other
unsigned for a
<, <=, > or >= expression.
-manfred
Interesting. I didn't know it was documented as being an
outright error, I thought it was just "surprising"...
I don't think Walter will ever accept to make it illegal
though, breaks too much code. If this was a change he was OK
with, I think we would have had it since day one, or at least,
years ago.
I remember hearing somewhere that D is about enforcing users to
write CORRECT code. I would really be disappointed with the
language if this sort of gotcha weren't eliminated.
If I look at this assert, I shouldn't be expecting it to pass.
static assert(-1 > cast(size_t)7);
IMHO, as long as this sort of comparison causes a compile-time
error, as the docs say they should, this kind of breaking
change is the of very good sort. The sort that reveals bugs in
code. (Like when they changed the NULL macro to mean 'nullptr'
instead of 0 in C++.) I couldn't imagine a programmer
exploiting this intentionally, as it serves no purpose.
I agree, breaking changes that expose bugs in your code are the
good kind. The time spent fixing compile time errors is more than
compensated for by the time saved not having to hunt down those
bugs.
Having worked with languages where reference types are
non-nullable by default I wish more languages did the same. More
often than not when a null makes it past the public interface to
an app or library then it is an error. So much code can be
simplified when the compiler looks a Null square in the mug and
declares, "thou shalt not pass!"
I dislike implicit conversions at the best of times, but implicit
conversions that change sign or drop bits is a design mistake
that needs to be fixed. I break out in convulsions at the sight
of them.
D has many great features [1] that help eliminate common errors,
but there still seems to be a few rough edges.
1.I recently learned about D's ability to write integers with
underscores, this is a great feature (if a bit tricky to generate
a lexer for [without handwritten code]).
I think that,
0b0010_1001__1101_1001__1101_1100__1101_100
is so much easier to grok, and to see a that a digit may be
missing from the end, effectively a right shift, than the
alternative
0b0010100111011001110111001101100
Only trip up is that 0b__1 == 0b1__ == 0b_1_ == 1 (for
understandable reasons, but something to keep an eye out for)
Related: std.algorithm.max *is* sign aware, and you can use
code such as:
if (a == max(a, b))
I have an pull request which creates the premise of functional
"less"/"greater" operators, which are also sign aware:
https://github.com/D-Programming-Language/phobos/pull/1365/files
*If* it goes through, and *if* we make them public in
std.functional, then it allows code such as:
int a = -1;
size_t b = 7;
assert(a.less(b)); //Passes
That is pretty cool, but unless the comparison operators
actually use that code, (which they probably won't, since it's
not a library thing?) it will only provide a workaround to the
problem.
