Attribute

An attribute is a named property of a Class that describes a range of values that can be held by the instances of that Class. You can specify attribute properties in the attribute's Specification window. Specifying attribute properties include changing the name, defining the type, converting the attribute to a port, etc. In the same window, you can find the description of each property. Descriptions are presented in the description area of the Specification window at the bottom of the Specification window.

New Attribute

To create a new attribute

There are quite a few ways to create a new attribute, so do one of the following:

• In the Containment tree, right-click a Class element, from the shortcut menu, select Create Element and then click Property, name it and press Enter.
• In the Class's Specification window, click Attributes on the left side of the window and then click the Create button. The Attribute Specification window opens. Type a desired name, then click Close. You will see the change directly on your Class symbol.
• On the diagram pane, click the Class shape, press the Ctrl+Alt+A shortcut keys and type the Attribute’s name and press Enter.
• On the diagram pane, click the Class shape and then click the Create Property, which is the white-circled plus on the side of the Class block, name your attribute and press Enter.
• On the diagram pane, click the Class shape, then click the Create Element button, which the black-circled plus on the side of the Class block. From the popped-up menu, select the Property command, name your attribute and press Enter. 

Attribute Name

The attribute's name must be unique in the Class scope. Nevertheless, do one of the following instructions to change the attribute's name. 

Example of changing the attribute name from 'country' to 'Country' 

To change an attribute name

• Click the Attribute in the selected Class on the diagram pane or in the Browser tree. Type a new name.
  
• Click on the Class block, double-click on the Attribute, and on the Attribute Specification window, change the name and click Close.
  
  

Attribute Type

To define the type of an attribute

• Do one of the following:
  • Open the Specification window of an Attribute in your Class block, by right-clicking on the Attribute, and click on the cell of the Type property value. Then click the  button. In the opened window, select the type. Click OK.
  • On the diagram pane, right-click the Attribute, and then point to Type. In the opened list, select the type or point to New to create a new type.
  • On the Class shape, click the Attribute, and then on the smart manipulator toolbar, click the  button. In the opened list, select the desired type.
  • On the Class shape, click the Attribute, and then click the Attribute the second time. After the Attribute name, type a colon ":" and then type in the name of the new attribute type. Click Enter or click anywhere on the diagram. The type is now created and assigned.

• In the Containment tree, select an element and drag it to the Attribute on the diagram.

Additional Information About Attribute Type

To add additional information about the type of an attribute

1. Open the Attribute Specification window, by right-clicking on the Attribute. 
2. In the top right corner of the window, select Expert in the Properties drop-down menu.
3. In the Type Modifier list, select a particular sign in the:
   1. & - one class has a reference to other model elements.
   2. * - one class has a pointer to other model elements.
   3. [] - one class has an array of other model elements.

Attribute Visibility

To set the attribute visibility

Do one of the following:

• Type '+', '~', '-', or '#' visibility marks just before an Attribute name directly on a diagram.
• Open the Attribute Specification window. From the Visibility drop-down list, select the desired item: public, package, protected, or private.

Attribute Scope

To set an attribute scope

1. Open the Attribute Specification window.
2. In the top right corner of the window, select Expert in the Properties drop-down menu.
3. Select the Is Static check box to true.

Attribute Multiplicity

To set the attribute multiplicity

1. Open the Attribute Specification window.
2. In the top right corner of the window, select Expert in the Properties drop-down menu.
3. Select or set the multiplicity value for the Multiplicity field.

Attribute Changeability 

The attribute changeability controls the access by operations on the class on the opposite end.

To set the attribute changeability 

1. Open the Attribute Specification window.
2. In the top right corner of the window, select Expert in the Properties drop-down menu.
3. Select the Is Read Only check box to true.

Convert Attribute To Association 

To convert an attribute to an association

1. On a diagram pane, select a Class with an Attribute, or select an Attribute itself.
2. From the Class's or Attribute's shortcut menu, select the Refactor command, then Convert To, and Association.
3. On the diagram pane, the Attribute is represented as an association with a role.

Convert Attribute To Port

To convert to a port 

1. Right-click an Attribute or multiple Attributes.
2. On their shortcut menu, click Refactor > Convert To > Port.