User Tools

Site Tools


method_syntax_overview.htm
Navigation:  Language Reference > App A - DDE, OLE, and OCX > Calling OLE Object Methods >====== Method Syntax Overview ====== Previous pageReturn to chapter overviewNext page

To call any OLE/OCX method, you use Clarion's Property Syntax. You specify the control to which the method or property belongs as the field equate label of the OLE control, then write the method call in a string constant inside the curly braces ({}).

The example code supplied with most OLE controls uses the VB/C++ “dot property” syntax to specify the name of the control and the method to call or the property to set. For example, the following VB code:

ControlName.AboutBox

translates to Clarion as:

?Ole{'AboutBox'}

This code displays the “About” dialog for the ControlName control. You might also see this example's VB code as:

Form1.ControlName.AboutBox

This form simply specifies the dialog containing the ControlName object. The Clarion translation for this is still the same.

The OLE/OCX object is always referenced in Clarion code by the field equate label of the Clarion OLE control, no matter what the name of the control is in VB, because the object's registered name is specified in the CREATE or OPEN attribute of the OLE control. Therefore, the Clarion runtime library only needs to know the field equate label to know exactly which object is being referenced.

Translating VB's “With” Syntax

Many OLE/OCX code examples use the VB With … End With structure to associate multiple property assignments and/or method calls with a single object. In this case, the object is named in the With statement and all the property assignments and method calls within the structure begin with the dot separator, then the name of the property to set or method to call. For example, the following VB code:

 With Form1.VtChart1

  'displays a 3d chart with 8 columns and 8 rows data

  .chartType = VtChChartType3dBar

  .columnCount = 8

  .rowCount = 8

  For column = 1 To 8

   For row = 1 To 8

    .column = column

    .row = row

    .Data = row * 10

   Next row

  Next column

  'use the chart as the backdrop of the legend

  .ShowLegend = True

 End With

translates to Clarion as:

!displays a 3d chart with 8 columns and 8 rows data

?Ole{'chartType'} = VtChChartType3dBar

?Ole{'columnCount'} = 8

?Ole{'rowCount'} = 8

LOOP column# = 1 TO 8

 LOOP row# = 1 TO 8

  ?Ole{'column'} = column#

  ?Ole{'row'} = row#

  ?Ole{'Data'} = row# * 10

 END

END

!use the chart as the backdrop of the legend

?Ole{'ShowLegend'} = True

Since Clarion has no direct equivalent to the VB With … End With structure, you just explicitly name the OLE control's field equate label on each property assignment or method call. The single quote (') in VB code indicates a comment.

VB allows nesting these With … End With structures, so you may need to “travel” back to find the object's name. This example demonstrates nested VB With structures:

With MyObject

.Height = 100                  ' Same as MyObject.Height = 100.

.Caption = “Hello World”       ' Same as MyObject.Caption = “Hello World”.

With .Font

 .Color = Red                  ' Same as MyObject.Font.Color = Red.

 .Bold = True                  ' Same as MyObject.Font.Bold = True.

End With

End With

which translates to Clarion as:

?Ole{'Height'} = 100            ! MyObject.Height = 100

?Ole{'Caption'} = 'Hello World' ! MyObject.Caption = “Hello World”

?Ole{'Font.Color'} = Red        ! MyObject.Font.Color = Red

?Ole{'Font.Bold'} = True        ! MyObject.Font.Bold = True

method_syntax_overview.htm.txt · Last modified: 2021/04/15 15:57 (external edit)