On Wed, 07 Jul 2010 00:47:32 +0200, BLS <windev...@hotmail.de> wrote:
Okay a bit better snippet than before. snippet should be almost
functional..
/*
Hi,
Andrei brings in the idea of std.pattern. Seems that this module is
"stalled"; Unfortunately !
However I would like to enhance collection classes (likewise
dcollections) with a Publisher - Subscriber pattern (signal - slot, or
observer pattern) , if you prefer)
Hope the idea of enhancing collections with events become clear with the
following snippet.
!!! I am able to spend just a few hours a month with D programming.. in
other words, please don't kill me :)
Untested Draft code which requires a lot of help and ,more important,
feedback from you.
*/
struct publisherMsg(T) {
T data;
Action a;
}
mixin template Publisher(T) {
private :
enum Action = {INSERT, UPDATE, DELETE, READONLY};
//alias typeof(this) PT;
struct receiver {
Object o;
callback cb;
}
receiver[] subscriber;
publisherMsg!(T) msg;
alias void delegate(const ref msg) callback;
void addSubscriber(object o, callback cb) {
//subscriber ~= o;
}
void publish() {
foreach (object o ; subscriber)
{
// create message and send message
}
}
}
mixin template Subscriber() {
// see UndoList for implementation
}
final class Stack(T, bool observable = false ) {
T[] data;
static if (observable) mixin Observable!T;
void push( T t) {
data ~= t;
publish(t, Action.INSERT);
}
T pop() {
publish(t, Action.DELETE);
//...
}
bool empty() {
}
T top() {
publish(t, Action.READONLY);
//...
}
size_t size() {
}
}
// Undo list will receive every pushed or popped item -data and action)
class UndoList(T) {
private:
T[] data;
/// should be part of the sunscriber mixin templates.
publisherMsg!T stackMessage;
void delegate(const ref stackMessage) dg;
alias Stack!(int) IntegerStack;
IntegerStack intstack = new IntegerStack;
private this() {
dg = &this.feedback;
// SUBBSCRIBE Stack(T) push and pop events.
intstack.addSubscriber(this, dg);
}
public void feedback(const ref stackMessage msg ) {
writefln("Action");
}
}
Hi Bjoern,
your mixin template should have "private { ... }" rather than "private:" I
believe the current way will make
everything that uses the mixin template private after its used.
