COMVariant.variant Method

Article
2014-04-11

Gets or sets the value of a COMVariant object of the VT_VARIANT (variant) data type.

Syntax

public COMVariant variant([COMVariant newValue])

Run On

Called

Parameters

newValue
Type: COMVariant Class
The new value; optional.

Return Value

Type: COMVariant Class
The current value.

Remarks

The variant property is used to nest one COMVariant object in another COMVariant object. When using the parent object as the argument in a call to COMDispFunction.call or in a call to the COM class, the called method will automatically extract the data of the nested object. This nesting facility is useful when a method on a COM object can work with multiple data types. Only one level of variant nesting is allowed.

If you pass in a value that has a different data type than the object, the data type of the object will be changed to match the data type of the value.

A COMVariant object has a variant type if its data type is set to COMVariantType::VT_VARIANT.

Examples

The following example creates a COMVariant object of type VT_I4 (long), and a COMVariant object of type VT_VARIANT. The object of type VT_VARIANT is assigned the value of the object of type VT_I4.

Note

The code below contains a hypothetical COM object ("MyCOM.Object"), and will therefore not run in Microsoft Dynamics AX, unless such an object is created outside Microsoft Dynamics AX.

{ 
    COM com; 
    COMDispFunction funcShow; 
  
    COMVariant var1 = new COMVariant( 
        COMVariantInOut::IN_OUT,  
        COMVariantType::VT_I4); 
  
    COMVariant var2 = new COMVariant( 
        COMVariantInOut::IN_OUT,  
        COMVariantType::VT_VARIANT); 
  
    InteropPermission perm1; 
    InteropPermission perm2; 
  
    // Set code access permission to help protect use of COM object 
    perm1 = new InteropPermission(InteropKind::ComInterop); 
    perm1.assert(); 
  
    com = new COM("MyCOM.Object"); 
  
    // Close code access permission for COM 
    CodeAccessPermission::revertAssert(); 
  
    // Set value of 'var1' 
    var1.Long(123456); 
    // Set value of 'var2' to 'var1' 
    var2.Variant(var1); 
  
    // Set code access permission to protect use of 
    // COMDispFunction object 
    perm2 = new InteropPermission(InteropKind::ComInterop); 
    perm2.assert(); 
  
    funcShow = new COMDispFunction( 
        com,  
        "Show",  
        COMDispContext::METHOD); 
 
    // Call funcShow with a long 
    funcShow.Call(var2); 
    // Change value of 'var1' 
     var1.BStr("Hello World"); 
    // Call funcShow with a string 
    funcShow.Call(var2); 
  
    // Close code access permission for COMDispFunction 
    CodeAccessPermission::revertAssert(); 
}

Share via