Denis Koroskin wrote:
On Wed, 28 Oct 2009 17:22:00 +0300, Andrei Alexandrescu
<seewebsiteforem...@erdani.org> wrote:
Walter has magically converted his work on T[new] into work on making
associative arrays true templates defined in druntime and not
considered very special by the compiler.
Wow, this is outstanding! (I hope it didn't have any negative impact on
compile-time AA capabilities).
This is very exciting because it opens up or simplifies a number of
possibilities. One is that of implementing true iteration. I actually
managed to implement last night something that allows you to do:
int[int] aa = [ 1:1 ];
auto iter = aa.each;
writeln(iter.front.key);
writeln(iter.front.value);
Two other iterations are possible: by key and by value (in those cases
iter.front just returns a key or a value).
One question is, what names should these bear? I am thinking of makign
opSlice() a universal method of getting the "all" iterator, a default
that every container must implement.
For AAs, there would be a "iterate keys" and "iterate values"
properties or functions. How should they be called?
Thanks,
Andrei
If AA is providing a way to iterate over both keys and values (and it's
a default iteration scheme), why should AA provide 2 other iteration
schemes? Can't they be implemented externally (using adaptor ranges)
with the same efficiency?
foreach (e; keys(aa)) {
writefln("key: %s", e);
}
foreach (e; values(aa)) {
writefln("value: %s", e);
}
Why would you prefer keys(aa) over aa.keys?
Last, I believe foreach loop should automatically call opSlice() on
iteratee. There is currently an inconsistency with built-in types - you
don't have to call [] on them, yet you must call it on all the other types:
Try implementing the range interface (front, popFront and empty), and
they are ranges. Magic! opApply is worth mentioning here, as well.
