Hi Philippe,
Ok, something more interesting it combines suggestion 2) and 3). Still
a quick hack, not much tested, but I think the intention is clear.
The snippets show how a publisher subscriber pattern can be mixed in.
Further it shows how a simple class could become a stack, queue, list etc.
The FooMixin was just to show (due to a question on D.Learn), how we can
mimic partial C# classes.
import std.stdio;
import std.cstream;
import std.functional;
void main(string[] args)
{
auto p = new PersonStack();
p.add("Hans", 42);// uses MIStack push(), MISubScriber notify()
din.getc();
}
mixin template MIPublisher()
{
alias void delegate(Object sender, string event) CallBack;
CallBack[] callBacks;
public void register(CallBack callBack)
{
callBacks ~= callBack;
}
// There is for sure a smarter solution to remove
public void unRegister(CallBack callBack)
{
for ( int i=0 ; !i<callBacks.length ; i++ )
{
if (callBacks[i] == callBack)
{
callBacks = callBacks[0..i] ~
callBacks[i+1..callBacks.length];
--i;
}
}
}
// Notify ALL Subscribers
public void notify(string evt)
{
foreach ( CallBack callBack ; callBacks )
{
callBack( this, evt );
}
}
}
mixin template MIStack()
{
alias typeof(this) Me;
//alias Me[] Us;
static Me[] stack;
public:
bool empty()
{
return stack.length == 0;
}
int count()
{
return stack.length;
}
void push(Me element)
{
stack ~= element;
}
Me pop()
{
Me element = peek();
stack.length = stack.length - 1;
return element;
}
Me peek()
{
if ( stack.length == 0 )
{
// throw error
}
Me element = stack[stack.length-1];
return element;
}
}
class PersonStack
{
private string name;
private int age;
// Our Mixins
mixin MIStack;
mixin MIPublisher;
this()
{
// Register some subscribers (MIPublisher register function)
// I have used free functions to show the useful toDelegate()
register( toDelegate(&DrawPersonBarChart) );
register( toDelegate(&DrawPersonPieChart) );
}
// Push
void add(string name, int age)
{
this.name = name;
this.age = age;
// Push Person (MIStack push function.)
push(this);
// Notify all subscribers
notify("Push");
}
// remove()
}
//Subscriber free functions
void DrawPersonBarChart(Object sender, string msg)
{
writeln("Bar " ~ msg);
}
void DrawPersonPieChart(Object sender, string msg)
{
writeln("Pie " ~ msg);
}
