Encapsulation and Protection Attributes

lesson#18 - Encapsulation and Protection Attributes/encap_protec_attrib.d

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+module encap_protec_attrib;
+
+// ***** public by default ******
+// => can be both accessed and modified
+struct Person {
+	string name;	// or => public string name;
+	int age;
+}
+
+// ****** private members ****** 
+// => cannot be modified, but can be accessed through get... functions
+struct Person2 {
+	private string name;
+	private int age;
+
+	string getName() {
+		return name;
+	}
+
+	int getAge() {
+		return age;
+	}
+}
+
+// specifying protection attributes at a modular level
+private void foo() { /* or struct/class/etc */ }
+
+// ****** package protection attribute ******
+// animal.cat contains: package void foo() { ... }
+// it can be accessed in any other module inside the animal package
+
+// ****** protected members ****** 
+// => can be accessed by the module that defines it and by any class that inherits from it
+class Person3 {
+	string name;
+	int age;
+
+	protected int id;
+
+	// this(...) { ... }
+	// ...
+}
+
+
+
+// ****** defining protection attribtes ****** 
+
+// 1) java style
+private void hello() { }
+
+// 2) c++ style
+public:
+	void hello() { }
+	// ...
+
+// 3) block style
+protected {
+	void hello() { }	
+}
+
+
+
+
+

lesson#18 - Encapsulation and Protection Attributes/main.d

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+import std.stdio;
+
+import encap_protec_attrib;
+
+void main() {
+	// John's members can be freely accessed and modified
+	Person John = Person("John", 35);
+	writeln("Person: ", John.name, ", ", John.age);
+
+	// Mary's members can be accessed through get... functions, but can't be modified
+	Person2 Mary = Person2("Mary", 21);
+	writeln("Person: ", Mary.name, ", ", Mary.age);				// ERROR! => no such property: name, age (because it's private)
+	writeln("Person: ", Mary.getName(), ", ", Mary.getAge());				// works! => a copy/value is returned
+}