On Tuesday, 17 February 2015 at 19:03:49 UTC, Chris Williams
wrote:
Every throwable function call could be assumed to have a typed
result (even void functions) and if, after the return, the
caller checks the type and detects that it was an error,
bubbles that up, then eventually you get to wherever the
catcher is.
But so basically, the current ABI doesn't support it and
there's no desire to change it? How do exceptions currently
happen, if not via some official ABI declaration of how
throwable methods interact with one another? The
compiler/linker determines where the catcher is and inserts
code to cut down the stack and perform a long jump all the way
back? If so, how do scope statements work?
No problem. in fact this kind of solution is a good fit for
language where try blocks are rare (say OCaml for instance) as
you can unwind much faster, while keeping the cost on the fast
path small.
But that wouldn't be a good fit for D (or even worse for C++)
because you have unwinding going on (destructor, scope
statements, ...) which makes for a lot of implicit try blocks.
