Andrei Alexandrescu wrote:
On 03/18/2010 01:49 PM, Walter Bright wrote:
Norbert Nemec wrote:
Regan Heath wrote:
So, these generators are essentially inline functions?
No. They may be inlined, but this is just an optimization just like
for regular functions. If they are not inlined, these generators are
simply functions with a special calling convention that allows them to
retain their local data and execution point on the stack in between
calls.
I did work out the assembly code for this some time ago and it worked
nicely. Very similar to what is needed for co-routines, but it is
possible to do everything on the stack.
How is that different from a local delegate that refers to local
variables of the function it is lexically nested in?
I think the difference is that e.g. a coroutine can repeatedly return
values from a loop. In contrast, the delegate must keep the state
separate, which may be a tad more complicated.
Right, the delegate would have to keep its persistent state in outer locals.
The trouble with a generator using the caller's stack is that then the generator
cannot recursively call itself (such as if it was walking a tree). In order to
work properly in the general case, a generator has to allocate all its local
variables on the heap.
