Attribute Syntax (UML Class)

Each attribute follows a certain syntax which is built up using the following structure:

1. Visibility: who is permitted to access the attribute
   • +: public / everyone
   • -: private / only the object itself
   • #: protected / class itself and sub-classes
   • ~: package / classes that are in the same package
2. Derived: / is specified if the attribute value is derived from other attributes
3. Name: name of the attribute
4. Type: it may be one of:
   • Another user-defined class
   • Predefined primitive data type (Boolean, Integer, String)
   • User-defined primitive data type: «primitive»

     	graph {
     		node[shape=record]
     		Float [label=<{«primitive» <br align="center"/><b>Float</b> <br align="center"/>| round(): void<br align="left"/>}>]
     	}

   • Composite data type: «datatype»

     	graph {
     		node[shape=record]
     		Float [label=<{«datatype» <br align="center"/><b>Date</b> <br align="center"/>| day<br align="left"/>month<br align="left"/>year<br align="left"/>}>]
     	}

   • Enumeration: «enumeration»

     	graph {
     		node[shape=record]
     		Float [label=<{«enumeration» <br align="center"/><b>AcademicDegree</b> <br align="center"/>| bachelor<br align="left"/>master<br align="left"/>phd<br align="left"/>}>]
     	}

5. Multiplicity: number of values an attribute may contain
   • By default, we take it to be $1$.
   • Notation is $[\text{min}\dots \text{max}]$.
   • No upper limit may be indicated by $[\ast ]$ or $[0\dots \ast ]$.
6. Default value: used if the attribute value is not set explicitly by the user
7. Properties: additional restrictions on attributes
   • Predefined properties that may be used:
     • {readOnly}: value cannot be changed
     • {unique}: no duplicates permitted
     • {non-unique}: duplicated permitted
     • {ordered}: fixed order of the values
     • {unordered}: no fixed order of the values
   • Common attribute specifications:
     • Set: {unordered, unique}
     • Multi-set: {unordered, non-unique}
     • Ordered set: {ordered, unique}
     • List: {ordered, non-unique}