On Saturday, 20 September 2014 at 09:05:24 UTC, Marc Schütz wrote:
On Saturday, 20 September 2014 at 08:32:55 UTC, Dicebot wrote:
On Saturday, 20 September 2014 at 08:20:47 UTC, Marc Schütz
wrote:
I don't think ARC is needed.
library RC + borrowing + uniqueness/moving = WIN
You can't do polymorphic entity RC (like exceptions) without
at least some help from compiler because language currently
does not provide tools for lifetime control of classes. At
least _some_ form of ARC is necessary.
I think we can, using templated alias this. We're not there
yet, but it's probably feasable, seeing that Igor Stepanov
already implemented multiple alias this [1]. With that and
maybe a little opDispatch magic, it should be possible to
making wrappers that are implicitly convertible to wrappers of
parents of their inner types.
Granted, for exceptions there's more needed: There needs to be
support for throwing and catching these wrappers, and for
catching wrappers of derived types, too. But note that
throw/catch itself doesn't involve copying, it's a moving
operation, which might make it easier.
[1] https://github.com/D-Programming-Language/dmd/pull/3998
Thinking further about it, we don't need templated `alias this`,
because we can just have one `alias this` that returns
`scope!this(T)` (this needs to be there anyway to be safe). It
would automatically behave like a normal class with regard to
polymorphy.
What's still needed then is a little magic to actually be able to
throw and catch the wrapper.
