Re: [ANN] Lua 5.2.0 (beta-rc1) now available

[David Given <dg@...>]

David Kastrup wrote:
[...]
> It would be nice if labels were callable in a
> similar way.

Algol-68 does this; a label can be cast to a parameterless function
pointer, Calling the function does a longjmp to the label, thus allowing
this sort of thing:

  proc openfile = (ref string filename, proc void onerror) int:
  (
    int fd = open(filename, "r");
    if (fd = -1) then
      onerror
    fi;
    fd
  );

  openfile("missing", abort);
  ...
  abort:
  print("Error!")

This provides a nice middle ground between simple labels and full-on
continuations --- but, of course, it's mostly useful for error recovery
as in the above example, and Lua's exceptions form a better way of
handling this.

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