#include <tclOO.h> const char * Tcl_OOInitStubs(interp)
When an extension library is going to use the C interface exposed by TclOO, it should use Tcl_OOInitStubs to initialize its access to that interface from within its *_Init (or *_SafeInit) function, passing in the interp that was passed into that routine as context. If the result of calling Tcl_OOInitStubs is NULL, the initialization failed and an error message will have been left in the interpreter's result. Otherwise, the initialization succeeded and the TclOO API may thereafter be used; the version of the TclOO API is returned.
When using this function, either the C #define symbol USE_TCLOO_STUBS should be defined and your library code linked against the Tcl stub library, or that #define symbol should not be defined and your library code linked against the Tcl main library directly.
If you are linking against the Tcl 8.5 forward compatibility package for TclOO, only the stub-enabled configuration is supported and you should also link against the TclOO independent stub library; that library is an integrated part of the main Tcl stub library in Tcl 8.6.