Advanced Programming Techniques in D/

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Property Functions

Property Functions

Learn about property functions that return values and property functions that are used in the assignment.

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Property functions that return values

As a simple example, let’s consider a rectangle struct that consists of two members:

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struct Rectangle {

    double width;

    double height;

}

void main() {}

Let’s assume that a third property of this type becomes a requirement, which should provide the area of the rectangle:

auto garden = Rectangle(10, 20);
writeln(garden.area);

One way of achieving that requirement is to define a third member:

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struct Rectangle {

    double width;

    double height;

    double area;

}

void main() {}

A flaw in that design is that the object may easily become inconsistent. Although rectangles must always have the invariant of “width * height == area ...