built-in array ptrEnd

[Jacob Carlborg]

On 2012-09-17 18:34, monarch_dodra wrote:
> I love D's concept of arrays (fat pointers).
>
> However, one thing I've found it lacks is a (convenient) way to get the
> end ptr.
>
> Phobos (and druntime) are riddled with "arr.ptr + arr.length". It is
> ugly and inconvenient, and makes something that should be easy to
> understand that much harder.
>
> Then I thought: "std.array" defines all the functions required to
> enhance arrays. Why not just add a "ptrEnd" in there? So I did.
>
> The rational is that now, we can write:
>
> bool isDisjoint = a.ptrEnd <= b.ptr || b.ptrEnd <= a.ptr;
>
> More elegant than:
>
> bool isDisjoint = a.ptr + a.length <= b.ptr ||
>                    b.ptr + b.length <= a.ptr;
>
> Nothing revolutionary, but it *is* easier on the fingers when typing :D
> . Also, it *does* make a change in some bigger and more complicated cases.
>
> Anyways, pull request:
> https://github.com/D-Programming-Language/phobos/pull/798
>
> I wanted to have some feedback, as this is introducing something new (as
> opposed to fixing something existing).
>
> IMO, this should really be built-in, in particular, since, in my
> understanding, an array is internally represented by the ptr and ptrEnd
> pair anyways. If the compiler has access to it, it might as well
> communicate it (rather than us re-calculating it...)

Rather than adding new language features we're moving stuff out of the 
core language and into the runtime/standard library. This is a perfect 
example of a library function. Since we have UFCS it would behave and 
look exactly the same as if it was a built-in property on arrays. If 
this is added to the "object" module in druntime you wouldn't even need 
to import anything.

-- 
/Jacob Carlborg