On Fri, 18 Oct 2013 16:43:23 +0100, Andrei Alexandrescu
<[email protected]> wrote:
On 10/18/13 3:44 AM, Regan Heath wrote:
On Fri, 18 Oct 2013 00:32:46 +0100, H. S. Teoh <[email protected]>
wrote:
On Fri, Oct 18, 2013 at 01:27:33AM +0200, Adam D. Ruppe wrote:
On Thursday, 17 October 2013 at 23:12:03 UTC, ProgrammingGhost
wrote:
>is null still treats [] as null.
blah, you're right. It will at least distinguish it from an empty
slice though (like arr[$..$]). I don't think there's any way to tell
[] from null except typeof(null) at all. At runtime they're both the
same: no contents, so null pointer and zero length.
I think it's a mistake to rely on the distinction between null and
non-null but empty arrays in D. They should be regarded as
implementation details that user code shouldn't depend on. If you need
to distinguish between arrays that are empty and arrays that are null,
consider using Nullable!(T[]) instead.
This comes up time and again. The use of, and ability to distinguish
empty from null is very useful.
I disagree.
Because.. the risk of a null pointer exception is not worth the gain? If
so, why not go the whole hog and prevent string from ever being null?
Then, at least we'd gain something from the loss of the null/empty
distinction/limitation.
D strings ought to decide whether they're reference types or value types,
if the former then I want consistent null back, if the latter then I want
to be rid of null for good. This middle ground sucks.
Yes, you run the risk of things like
null pointer exceptions etc, but we have that risk now without the
reward of being able to distinguish these cases.
Take this simple design:
string readline();
This function would like to be able to:
- return null for EOF
- return [] for a blank line
That's bad API design, pure and simple. The function should e.g. return
the string including the line terminator, and only return an empty (or
null) string upon EOF.
It's the C# ReadLine() design and I've never once had a bug because of it.
R
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