Returning Floats and Doubles from Automation methods

• Microsoft OLE Libraries for Windows and Win32s, version 2.02

SUMMARY

Automation properties or methods implemented with the C calling convention in the Windows 16-bit operating system can't return type Float or Double. This includes the Date type, which is a floating-point type. To work around this, you can implement them using the Pascal calling convention.

MORE INFORMATION

Automation methods and properties can be marked as using one of the calling conventions described by the CALLCONV enumeration. This calling convention is used by the standard IDispatch implementation provided by CreateStdDispatch and by DispInvoke to call property accessor functions or methods. Note that the an automation controller does not directly use these calling conventions.

Because of a C Language implementation limitation, automation properties and methods that return Float or Double cannot use the C calling convention. You need to use the Pascal calling convention.

For example, describe a method or automation property that returns a Float or Double as follows in the .ODL file:

[propget] float pascal MyProperty(); float pascal MyMethod();