You wrote:
Object instproc insert_mixin {mixin_list} { my mixin [append mixin_list " " [my info
mixin]]
}with names like mixinappend, mixinprepend for mixins,
filters,
instmixins, instfilters we would introduce a large number
of
methods, which do more or less the same.
Yes. That is certainly a problem.
what do you people think about the following "interceptor" method: it is more verbous, but much more powerful as
well; it
allows appending/prepending/inserting at a certain
position and
deletion of all kinds of interceptors:
Hm...
One minor niggle is the use of the term 'interceptor'. The term is quite overloaded. First, this instproc manages two kinds of 'interceptor' interfaces for an object: mixins and filters. Second, the proc itself is an interceptor -- it traps calls to manage the mixin and filter lists. Third, as you have written this proc, it manages both mixins and filters, which makes them appear more similar than they really are.
That said, I do think you are on to something. The core problem is that both filters and mixins are a list of classes, and there are no good primitives to manage that list in a natural manner. It would be nice if [my info mixin] and [my info filter] were mutable with list commands, but...
So, for the sake of argument, let us assume that there are two new instprocs - one to manage the list of filters, and one to manage the list of mixins (again, better naming ideas greatly appreciated):
Object instproc mixin_list args { set op [lindex $args 0] set classes [lrange $args 1 [llength $args]]
switch -exact $op { append { my mixin [concat [my info mixin] $classes] } prepend { my mixin [concat $classes [my info mixin]] } set { my mixin $classes } get { my info mixin } delete { ... } } }
Class A Class B Class C
A a a mixin_list append B a mixin_list prepend C a mixin_list get ================ ::C ::B
Adding new primitive operations (like a mixin_list length; a mixin_list sort; a mixin_list contains classname; etc.) is simple and obvious. I haven't played with filters yet, but this idiom should work well there, too.
I'll leave it to you to determine whether this method should work use instmixin for Classes, and mixin for Objects.
-- Adam