Creating Excel add-ins from scratch is not trivial, as anyone who has attempted to do so using the Microsoft Excel SDK soon realizes. A good exercise would be to download that and attempt to create your own add-in.
Back already? I can't blame you.
An xll add-in is just a dll with well-known entry points. When the add-in is opened,
Excel looks for a function called xlAutoOpen
and calls it. When the
add-in is closed, Excel looks for a function called xlAutoClose
and
calls that. The job of xlAutoOpen
is to register functions that can
extend the functionality of Excel, while that of xlAutoClose
is to
unregister the functions.
The xll library provides these functions for you so you don't have to write them.
All you need to do is create AddIn
objects with the information Excel
needs to register and unregister add-in functions and macros. Click on each class
to learn more.
class description AddIn
The class for creating Excel add-in functions and macros. OPER
The variant datatype corresponding to a cell or range of cells. Excel
Calls Excel internal functions and macros. Register
Call xlfRegister
with the appropriate arguments.Args
Arguments passed to Register
.FP
A two dimensional array of floating point numbers.