Q191872: PRB: Enum HelpStrings Not Displayed in Properties Window
Article: Q191872
Product(s): Microsoft Visual Basic for Windows
Version(s):
Operating System(s):
Keyword(s): kbGrpDSVB
Last Modified: 11-JAN-2001
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The information in this article applies to:
- Microsoft Visual Basic Learning Edition for Windows, versions 5.0, 6.0
- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0
- Microsoft Visual Basic Standard Edition for Windows, version 4.0
- Microsoft Visual Basic Professional Edition for Windows, version 4.0
- Microsoft Visual Basic Enterprise Edition for Windows, version 4.0
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SYMPTOMS
========
HelpStrings of Enum types in an ActiveX control developed in Visual C++ are not
displayed in the Properties Window of Visual Basic 5.0 and 6.0. This behavior
differs from previous versions of Visual Basic.
CAUSE
=====
When an ActiveX control is developed in Visual C++, Enum types can be declared
in the control's ODL file, and subsequently used by the control's properties.
HelpStrings can also be associated with the members of the Enum to help define
the property.
Here is a segment of an ODL file for an ActiveX control built in MFC:
typedef enum tagLineStyleConstants
{
[helpstring("Solid")] lsSolid = 0,
[helpstring("Dash")] lsDash = 1,
[helpstring("Dot")] lsDot = 2,
[helpstring("Dash-Dot")] lsDashDot = 3,
[helpstring("Dash-Dot-Dot")] lsDashDotDot = 4,
} LineStyleConstants;
....
properties:
// NOTE - ClassWizard will maintain property information here.
// Use extreme caution when editing this section.
//{{AFX_ODL_PROP(CEnumCtrl)
[id(1)] LineStyleConstants LineStyle;
//}}AFX_ODL_PROP
When the ActiveX control has been sited on a form in Visual Basic 4.0, you can
see that the value of the LineStyle property, when viewed from the Properties
Window, is composed of all the HelpStrings of the Enum type. It looks similar to
the following:
0 - Solid
1 - Dash
2 - Dot
3 - Dash-Dot
4 - Dash-Dot-Dot
However, when this ActiveX control is sited on a form in Visual Basic 5.0 or 6.0,
you can see that the value of the LineStyle property is composed of all the
members of the Enum type rather than the HelpStrings. It looks similar to the
following:
0 - lsSolid
1 - lsDash
2 - lsDot
3 - lsDashDot
4 - lsDashDotDot
Visual Basic 5.0 or 6.0 reserve the HelpStrings for descriptive explanations of
each Enum member when viewed in the Object Browser.
RESOLUTION
==========
There are several solutions for this issue:
1. Make the name of each element in your Enum types as meaningful as possible so
users of your control could figure out its meaning from the name.
2. Implement the members of the IPerPropertyBrowsing interface, which allow
clients to query your control for descriptive strings for properties viewed
from a Property Page and Visual Basic's Properties Window.
3. Create property pages for your properties. The Enum HelpStrings will be used
in property pages.
For additional information regarding solution 2 or 3 above, please refer to
the following article in the Microsoft Knowledge Base:
Q141488 SAMPLE: Using Enumerated Properties in an OLE Control
STATUS
======
This behavior is by design.
MORE INFORMATION
================
Steps to Build an ActiveX Control in MFC
----------------------------------------
1. Start Visual C++ 5.0 and create a new control project using the MFC ActiveX
ControlWizard. Name the project EnumTest, and click OK. When the wizard comes
up, press Finish to accept the default settings.
2. From the ClassView tab, right-click on _DEnumTest and select "Add Property"
from the context menu. Add the name LineStyle to the dialog's External Name
text box, and choose long as the data type. Accept the default variable name
and function by click OK.
3. From the Files tab, open the EnumTest.odl file and add the following inside
your type library, just under the importlib(STDTYPE_TLB) statement:
typedef enum tagLineStyleConstants
{
[helpstring("Solid")] lsSolid = 0,
[helpstring("Dash")] lsDash = 1,
[helpstring("Dot")] lsDot = 2,
[helpstring("Dash-Dot")] lsDashDot = 3,
[helpstring("Dash-Dot-Dot")] lsDashDotDot = 4,
} LineStyleConstants;
4. Continue down and change the data type for the newly-added property from a
long to the enum type LineStyleConstants:
// NOTE - ClassWizard will maintain property information here.
// Use extreme caution when editing this section.
//{{AFX_ODL_PROP(CEnumTestCtrl)
[id(1)] LineStyleConstants LineStyle;
//}}AFX_ODL_PROP
5. Compile your control. MFC will register the control for you.
Steps to Test the Control in Visual Basic
-----------------------------------------
1. Open Visual Basic and create a new Standard EXE project. Form1 is created by
default.
2. From the Project|Components menu, add the control EnumTest.ocx to the Visual
Basic Toolbox.
3. Add an instance of the EnumTest.ocx control to Form1.
4. From the Properties window, look for the LineStyle property. You can change
the value of the LineStyle property from the dropdown combobox. On Visual
Basic 4.0, these items will be composed of the Enum type HelpStrings. On
Visual Basic 5.0 and Visual Basic 6.0, the member names themselves will
appear.
Additional query words: kbDSupport kbDSD kbVBp kbVBp400 kbVBp500 kbVBp600 kbCtrlCreate kbVC500 kbWizard
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Keywords : kbGrpDSVB
Technology : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600 kbVB400Search kbVB400
Issue type : kbprb
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