Knowledge Base

PRB: Class Browser: "Unable to Display Class Hierarchy" Error

Article ID: 136848

Article Last Modified on 2/15/2000

Microsoft Visual FoxPro 3.0 Standard Edition

This article was previously published under Q136848

SYMPTOMS

When a Class library is browsed in the Class Browser and a class that has subclasses is removed, the error "Unable to Display Class Hierarchy" is displayed when the Class Browser form is refreshed.

CAUSE

A class contains an explicit reference to its parent in a .vcx file. If the parent class is removed, the derived class cannot find its parent, and the class hierarchy is incorrect.

RESOLUTION

Remove the child classes first, and then delete the parent class.

STATUS

This behavior is by design.

MORE INFORMATION

Steps to Reproduce Behavior

Start the Class Browser (On the Tools menu, click Class Browser).
Open a class that has some child classes. For example, open the Tsbase.vcx file located in the Vfp\Mainsamp\Libs directory.
Click the Remove button to delete a class that has derived classes. For example, delete TSBASEFORM. The error "Unable to Display class hierarchy" is displayed.

Additional query words: VFoxWin

Keywords: KB136848