Hi Donal,

On 07/05/2008, at 16:57, Donal K. Fellows wrote:

>  Daniel A. Steffen wrote:
> > How do I create a metaclass destructor though (without going  
> > through the root oo::object destructor as in my example)? wouldn't  
> > I need self.destructor? (or maybe I'm getting (meta)confused given  
> > the hour ;-)
> 
>  oo::class create metaclass {
>    superclass oo::class
>    destructor { ... }
>  }
>  metaclass create ordinaryclass {
>    ...
>  }
>  ordinaryclass create instance

ah yes, of course, cool, that works nicely, c.f. below.

minor question about API naming consistency that occurred to me while  
playing with this:

why is it [oo::define superclass] but [info class superclasses]? both  
deal with a list of classes, so why not 'superclasses' in both cases?

> > this appears to be triggered by the fact that L is a subclass of  
> > the class to be mixed into (i.e. oo::object).
> > maybe mixing into oo::object needs to be made an exception for the  
> > TclOOIsReachable() check in TclOODefineMixinObjCmd()?
> 
>  Umm, yes. Chalk that one up as a bug. Please file an issue report  
>  so I remember to fix it. :-)

ok, will do

> > when mixing L into oo:class instead, the mixed-in destructor did  
> > not get called at class destruction, is it not possible to mixin  
> > destructors?
> 
>  Not at the moment. Are you arguing that that's a bug? (I can fix it  
>  if you are... :-))

my intuition would be that constructor/destructor of mixins should be  
called, given that mixin methods can access instance variables of the  
mixin class, which may need to be setup/torn down. FWIW, that is also  
what XOTcl appears to be doing. Will file a bug.

Cheers,

Daniel

-- 
** Daniel A. Steffen                   **
** <mailto:das@[...].net>   **

#---------------------------------------------------------------
puts "TclOO [package require TclOO]:"

##destruction logging:
oo::define oo::object destructor {puts "  [self] destroyed"}

oo::class create M {
     superclass oo::class
     destructor {
	set sups [info class superclasses [self]]
	foreach sub [info class subclasses [self]] {
	    set subsups [info class superclasses $sub]
	    set i [lsearch -exact $subsups [self]]
	    oo::define $sub superclass {*}[lreplace $subsups $i $i {*}$sups]
	}
	foreach inst [info class instances [self]] {
	    set sup [lindex $sups 0]
	    oo::define $inst self.class $sup
	}
	next
     }
}
M create A {}
M create B {superclass A}
puts " class  B with superclasses [info class superclasses B]"
A create O
puts " object O of class [info object class O]"
puts "destroying A:"
A destroy
puts " class  B with superclasses [info class superclasses B]"
puts " object O of class [info object class O]"
puts "destroying B & O:"
B destroy; O destroy

#---------------------------------------------------------------
# TclOO 0.2:
#  class  B with superclasses ::A
#  object O of class ::A
# destroying A:
#   ::A destroyed
#  class  B with superclasses ::oo::object
#  object O of class ::oo::object
# destroying B & O:
#   ::B destroyed
#   ::O destroyed
#---------------------------------------------------------------


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