selective error catching

Well, it doesn't have to be efficient. If there is no error, the code doesn't have to run, and most of the time there shouldn't be any error. (Right?)

A combination could work too, so you can put the declaration at "try" once and for all if you're in that mood,

try { ... } catch (object err; err->is_my_error && err->failure_pos > 4711) { ... }

<=>

try (object err) { ... } catch (; err->is_my_error && err->failure_pos > 4711) { ... }

and

try (object err) { ... } catch (MyError err) { ... } catch (; err->is_my_error && err->failure_pos > 4711) { ... }

(I'm more of the catch MyError type though, given that the typesystem works.)

If the typesystem can't support this, however, the branch of discussion goes to the bitbucket. :)