What's left for 1.0?

[Benji Smith]

Bill Baxter wrote:
 > So, what's left on everyone's lists for D1.0 must-have features?

Although D doesn't currently use a generational copying collector, it 
would be nice if we could anticipate the hurdles to implementing a 
copying GC in the current language, and develop some syntactic 
extensions to the language for copying with a copying GC.

In a language like Java, where there are only reference types and 
primitives (i.e., no pointers), the implementation of a copying GC is 
pretty straightforward, because when an object gets moved to a new 
location in memory, you never have to worry that it will leave behind a 
orphaned pointer.

In C#, which does allow pointers, certain blocks of code are marked as 
unsafe, and certain objects or pointers can be temporarily "pinned" to 
their current memory location. If the GC thread comes to life during the 
execution of an unsafe block, the GC will ignore any objects or pointers 
that have been pinned at their current location. Those items will be 
collected later, during a subsequent GC run, after they've been "un-pinned".

It would be nice, before version 1.0 of D, to get the syntax in place 
for pinning pointers. With the current GC, all objects are permanently 
"pinned" anyhow, so this implementation would be semantically correct, 
even if it didn't do anything :) But at least, with the syntax in place, 
we'd be prepared for the eventual introduction of a generational copying 
GC, when such a thing is inevitably implemented.

--benji