Classes vs. Structs in D

lesson#17/main.d

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+import std.stdio: writeln;
+
+// classes are a reference type, structs are a value type
+class Hello {
+	string name;
+
+	this(string s) {
+		name = s;
+	}
+
+	void print() {
+		writeln("hello, ", name, "!");
+	}
+
+	// a func for copying an object
+	Hello dup() {
+		return new Hello(name);
+	}
+}
+
+void main() {
+	// class initialization
+	Hello hello = new Hello("John"); 	// use -vgc flag to display GC allocations
+
+	// allocating on the stack using "scope" keyword
+	//scope Hello hello = new Hello("John");
+
+	if(hello is null) {
+		writeln("Error! Could not initialize hello!");
+		return;
+	}
+
+	/*  scope(...) { ... } expressions:
+			scope(success) { ... } 	=>	is executed if the scope exits successfully
+			scope(failure) { ... }	=>	is executed if the scope exits due to an exception
+			scope(exit) { ... }		=>	is executed regardless of the previous two cases
+	*/
+
+	scope(exit) {
+		writeln("goodbuy...");
+	}
+
+	hello.print();
+
+	// making a reference
+	Hello ref_hello = hello;
+
+	// making a copy
+	Hello copy_hello = hello.dup();
+}
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