C++ API Design Best Practices - UML Class Diagrams

Box that is segmented into three parts

• The upper section contains the class name.
• The middle section lists the attributes of the class.
• The lower section enumerates the methods of the class.

Symbol to indicate the access level, or visibility, for that attribute or method.

• + indicates a public class member
• - indicates a private class member
• # indicates a protected class member

Relationships between classes are illustrated with various styles of connecting lines and arrowheads.

• Association: A simple dependency between two classes where neither owns the other, shown as a solid line.
• Association can be directional, indicated with an open arrowhead such as “>”.
• Aggregation: A “has-a,” or whole/part, a relationship where neither class owns the other, shown as a line with a hollow diamond.
• Composition: A “has-a” relationship where the lifetime of the part is managed by the whole. This is represented as a line with a filled diamond.
• Generalization: A subclass relationship between classes, shown as a line with a hollow triangle arrowhead.

Specify Multiplicity whether the relationship is one to one, one to many, or many to many.

• 0..1 = Zero or one instances
• 1  = Exactly one instance
• 0..* = Zero or more instances
• 1..* = One or more instances