PRB: Creating Instance of OLE Control Causes Exception Error

ID: Q132568

The information in this article applies to:

Microsoft Visual FoxPro for Windows, version 3.0

SYMPTOMS

When creating simultaneous instances of OLE automation objects, Visual FoxPro displays this error:

OLE error Code

Under some circumstances, an exception error is generated in one of the server applications. This behavior occurs when one of the OLE objects is an OLE control (OCX).

CAUSE

This error results from creating an instance of an OLE control with the following syntax:

Oobject1=CREATEOBJECT(<olecustomcontrol>)

OLE Automation objects (OCX) are not designed to be standalone automation servers.

WORKAROUND

Place the OLE control in an OLE container instead of creating an instance of the OLE control. The following example illustrates this method. It uses the outline control that ships with Visual FoxPro.

Example code


oMyform=CREATEOBJECT('new_form')
oMyform.SHOW

* The following lines add three items to the outline control.

oMyform.myoutline.ADDITEM('VFP',0)
oMyform.myoutline.indent(0)=1
oMyform.myoutline.ADDITEM('Samples',1)
oMyform.myoutline.indent(1)=2
oMyform.myoutline.ADDITEM('Controls',2)
oMyform.myoutline.indent(2)=3
READ EVENTS

* Form class definition. The form contains a command button and an
* olecontrol

DEFINE CLASS new_form AS FORM
   AUTOCENTER=.T.
   BACKCOLOR=RGB(192,192,192)
   WIDTH= 220
   HEIGHT= 200
   CAPTION= "Using the outline control"
   ADD OBJECT myoutline AS outlinecontrol
   ADD OBJECT mycmd AS cmdquit WITH TOP=120, LEFT=80
ENDDEFINE

* Defines the Ole container control. The OLE class is MSOutl. Outline.
* The Outline control is used.
DEFINE CLASS outlinecontrol AS OLECONTROL
   OLECLASS = "MSOutl.Outline"
   LEFT=12
   Top=12
   Width=170
   Height=80
   FontSize=10
   FontName="Arial"
   FontBold=.F.
   FontItalic=.T.
ENDDEFINE

Class Definition for Command Button


* Class definition for the command button. When users click the command
* button, the form is released.

DEFINE CLASS cmdquit AS COMMANDBUTTON
   Width=40
   Height=25
   Caption = "Quit"

   PROCEDURE CLICK
      RELEASE ThisForm
      CLEAR EVENTS
   ENDPROC
ENDDEFINE

MORE INFORMATION

Code to Reproduce Behavior


ON ERROR ? "-------------------------> "+message()
oObj1=CREATEOBJECT("Word.Basic")
oObj2= CREATEOBJECT("Excel.Sheet")
oObj5= CREATEOBJECT('msoutl.outline')
ON ERROR

Additional query words: VFoxWin crash

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