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# Hierarchy Browser

Inheritance, a type of relationship between objects, allows one object to share behavior with one or more other objects. Inheritance provides a basic mechanism for the reuse of code. Sharing with more than one is known as multiple inheritance.

The Hierarchy Browser can display the entire class hierarchy, including the superclasses and subclasses of a selected class. This helps you understand class hierarchy trees, which in turn helps you to reuse existing code.

A baseclass is a top-level class in the class hierarchy. It does not inherit from any other class; other classes inherit from it.

A class a is said to be a superclass of class b when class b inherits from a or another class that inherits from a.

A class a is said to be a subclass of class b when class a inherits from b or another class that inherits from b.

If class a is a superclass of class b, then class b is a subclass of class a.

## Using the Hierarchy Browser

Start the Hierarchy Browser in one of the following ways:

- from the Windows menu, select New View -> Hierarchy.

- click the Hierarchy toolbar button.

- choose the Hierarchy tab in the Editor.

Hierarchy Browser Window

### Tools Menu

The Hierarchy menu, accessed from the Tools menu, contains the following items, which control how the class hierarchies are displayed.

Show Superclasses

Limits the hierarchy to the superclasses (and their subclasses) of the selected class.

Show Subclasses

Limits the hierarchy to the subclasses of the selected class.

Show All

This is the default for this menu.

Display file names

Displays the file names of the superclasses and subclasses.

### Class/Hierarchy Preferences

Many of the settings that control how the Hierarchy Browser window functions are located in the Class/Hierarchy tab of the Preferences dialog. To find this dialog:

1. In the Symbol Browser, from the File menu, select Project Preferences. In the Hierarchy Browser, from the File menu, select View Preferences.

2. Choose the Class/Hierarchy tab.

Class/Hierarchy Tab of the Preferences Dialog

##### Class

Go To

Select Declaration if you want the Class Browser to display the prototype of the function; select Implementation if you want to see the actual code.

Orientation

Select Horizontal to have the Hierarchy Browser appear below the Class Browser; select Vertical to have the Hierarchy Browser appear to the right of the Class Browser.

Display members

Select First to cause instance variables to appear before methods in the Class Browser; select Second to cause methods to appear first, with the instance variables after them.

##### Hierarchy Layout

Display order:

Left to right displays the hierarchy from left to right in the main window; Top to Bottom displays the hierarchy from top to bottom.

Display layout style:

Select Tree to display the hierarchy in tree layout; select ISI to display the hierarchy in ISI layout.

Vertical space:

Enter the number of vertical pixels between symbols in the Hierarchy Browser window.

Horizontal space:

Enter the number horizontal pixels between symbols in the Hierarchy Browser window.

### Hierarchy Browser Shortcut Keys

This shortcut key is available for use with the Hierarchy Browser.

Key Combination | Function
UNIX | Windows |
Meta+B (or Alt+B) | Alt+B | Starts the Class Browser for the marked class.

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