Problem Statement

Show how to call a function in a shared library (without dynamically linking to it at compile-time). In particular, show how to call the shared library function if the library is available, otherwise use an internal equivalent function. This is a special case of calling a foreign language function where the focus is close to the ABI level and not at the normal API level.

Let's start with the solution:

'Loading a shared library at run time and calling a function.

declare MessageBox(sys hWnd, String text,caption, sys utype)

sys user32 = LoadLibrary "user32.dll"

if user32 then @Messagebox = getProcAddress user32,"MessageBoxA"

if @MessageBox then MessageBox 0,"Hello","OxygenBasic",0

'...

FreeLibrary user32