On 08.08.2010 17:51, bearophile wrote:
simendsjo:
auto a = [1:2];
auto p = 1 in a;
// can p be invalidated by rehashing?
Yes, I presume it can. p is meant for immediate consumption only.
// The spec also says it orders in place, but returns the reorganized
array...
// Is the spec right? That it rehashes in place and returns a reference
to
// itself?
assert(a is b);
Yes, a and b are meant to be equal, because they are a reference, that doesn't
change. What changes is the data structures referenced by it (if what I have
just said turns out to be wrong, then probably it's an implementation bug that
needs to be added to bugzilla).
Ok, thanks.
auto a = [1:2];
auto p = 1 in a;
a.remove(1);
// the memory for p can be reassigned by the gc,
// so this is undefined behavior.. right?
Right, such things show that it's probably better to change the D AA design
here:
1) make "x in AA" return a bool
2) improve dmd so it is able to remove most cases of dual lookups in AAs.
I will think if this needs to become an enhancement request.
1)
I haven't worked much with AA's, but I find the "key in aa returns a
reference to the value" to be handy. I think it's better than the following:
int value;
if( 1 in a )
value = a[1];
or a[1] in a try/catch or other implementations.
2) I don't know what you mean. Does a single lookup often involve
several under the hood?
