68 lines
891 B
D
68 lines
891 B
D
import std.stdio: writeln;
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interface IObserver {
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void update(string msg);
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}
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class WhatsApp {
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private IObserver[] list;
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this() {}
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~this() {}
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void addClient(IObserver o) {
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list ~= o;
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}
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void removeClient(IObserver o) {
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import std.algorithm: remove;
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list = list.remove!(a => a is o);
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}
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void notify(string msg) {
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foreach(client; list) {
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client.update(msg);
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}
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}
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}
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class Person: IObserver {
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string name;
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this(string name) {
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this.name = name;
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}
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void update(string msg) {
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writeln(name, "\t: notified. [", msg, "]");
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}
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}
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void main() {
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WhatsApp app = new WhatsApp();
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Person anna = new Person("Anna");
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Person john = new Person("John");
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Person markus = new Person("Markus");
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app.addClient(anna);
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app.addClient(john);
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app.addClient(markus);
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app.notify("hello, world!");
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app.removeClient(john);
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app.notify("john left the conversation");
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}
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