Professional Excel Development [Electronic resources] : The Definitive Guide to Developing Applications Using Microsoft® Excel and VBA® نسخه متنی

Miscellaneous Topics

A Caution for Users of COM Automation

A function that is defined in an XLL can be called in three situations:

During the recalculation of a workbook

As a result of Excel's Function Wizard being called to help with the XLL function

As a result of a VBA macro calling Excel's Application.Run method

Under the first two circumstances, Excel's object model does not expect and is not prepared for incoming Automation calls. Unexpected results or crashes may occur if you use COM Automation under these circumstances.

C++ Keyword Clash with the XLOPER Definition

To compile xlcall.h in a C++ project (as opposed to the C project demonstrated here) using a standards-compliant C++ compiler (such as VC.NET), you must add the following wrapper around the xlcall.h include. This is because the bool variable name used in the XLOPER struct definition is now a C++ keyword.

#define bool boolean
#include "xlcall.h"
#undef bool