primitive value overflow

[Mr. Anonymous]

On Thursday, 16 May 2013 at 21:04:38 UTC, Jonathan M Davis wrote:
> On Thursday, May 16, 2013 22:42:23 luka8088 wrote:
>> I agree that it is exactly the same as checking if 
>> (text1.length >
>> text2.length). And I don't think that this is an issues if you 
>> are aware
>> of the fact that you are working with unsigned values. But in 
>> the code
>> that I wrote there was no mentioning of unsigned so the 
>> possibility of
>> that kind of issue never came to mind until I actually printed 
>> the
>> values. And that is what I wanted to emphasize.
>
> Well, I'm not sure what can be done about that. length is 
> size_t, which is the
> unsigned integral value which matches the architecture (uint 
> for 32-bit and
> ulong for 64-bit). AFAIK, the documentation is clear on this 
> (though I haven't
> read it recently). If it's not, then it should be made clearer, 
> but using
> size_t for length is pervasive in D as it is in C++, and if you 
> know the
> standard types, you know what size_t is.
>
> As for overflow checking, it's come up quite a few times, and 
> Walter is
> completely against it. The hardware doesn't support it, and it 
> would definitely
> be slow if it were added. The standard way to handle that if 
> you want it is to
> create user-defined integral type which does the checks (though 
> that obviously
> won't help you when you can't control the types that you're 
> dealing with). But
> if you want to add checks in your code, you can always create a 
> wrapper
> function for doing the subtraction. And if you wanted the 
> checks to only be
> there in non-release mode, then you could even put the checks 
> in a
> version(assert) block. So, you can add checks if you want them, 
> but there's
> pretty much no way that how unsigned or overlflow are handled 
> in the language
> is going to change.
>
> - Jonathan M Davis

I agree with Walter if we're talking about production code, but I 
think it could be very helpful for debug builds.

P.S.
> The hardware doesn't support it
That's not completely true.
e.g. x86, while it doesn't throw an exception on an overflow, it 
does set a flag, which could be relatively cheaply checked.