[EMAIL PROTECTED] wrote:
It would behave like a tied sub (or method), with a .dispatch method to decide which of the contained routines should be called this particular time. Manhattan would be the default. However, one can override the dispatch logic; implementing Luke's Patterns idea, for example.Hmm, that ties into my wishlist item. Would it be possible to implement method combinators (or rather, multimethod combinators) from Common LISP in addition to this? The only CLOS feature that A12 doesn't mention, can't let that happen. ;)
class A { ... }
class B is A { ... }1> multi foo ($a) is before { ... }
2> multi foo (B $a) { ... next METHOD; ...}
3> multi foo (A $a) { ... }
4> multi foo ($a) is after { ... }
5> multi foo ($a) is around { ... next METHOD; }
6> multi foo ($a) is before { ... }.... and this runs all 5 methods, in order 5 > 1 > 2 > 6 > 3 > (returns to 2) > 4 > (returns to 5)
And yes, 6 and 1 do have the same signature. The rule is to run all before methods in order of the currently selected distance (ties broken in random order ;) ), and all after methods in the reverse order.
Oh, and the reason why around methods are useful?
multi foo ($a) is around {
CATCH { ... }
next METHOD;
}Note that this catches the exceptions thrown by any version of foo, even though at this point you don't know whether foo will be specialised. before methods aren't useful for this since their stack frame and handler blocks don't linger during the executions of other methods.
Common LISP references:
Standard method combination (before, after, around) http://www.lispworks.com/documentation/HyperSpec/Body/07_ffb.htm
Other method combinations (+, and, etc) http://www.lispworks.com/documentation/HyperSpec/Body/07_ffd.htm
Creating your own method combinations (define-method-combination) http://www.lispworks.com/documentation/HyperSpec/Body/m_defi_4.htm
Come to think of this, it seems that the only thing that'd need to be modified to accomodate both Rod's and mine proposal is to move CALLONE and CALLALL from the class to be MMD object somehow. Perhaps
multi CALLONE ($obj, $method where { $_ == &func }, [EMAIL PROTECTED]) { ... }Hmm, but this syntax strikes me as icky.
Miro
