In a header file of your C/C++ application or extension that includes the Tcl library, add these lines:
#include <tcl.h>
...
#if ((TCL_MAJOR_VERSION < 8) || ((TCL_MAJOR_VERSION == 8) \
&& (TCL_MINOR_VERSION == 0)))
typedef struct Tcl_SavedResult {
char *result;
Tcl_FreeProc *freeProc;
} Tcl_SavedResult;
extern void Tcl_DiscardResult _ANSI_ARGS_((Tcl_SavedResult *));
extern void Tcl_RestoreResult _ANSI_ARGS_((Tcl_Interp *, Tcl_SavedResult *));
extern void Tcl_SaveResult _ANSI_ARGS_((Tcl_Interp *, Tcl_SavedResult *));
#endifSomewhere in your program/library code, add these lines:
#if ((TCL_MAJOR_VERSION < 8) || ((TCL_MAJOR_VERSION == 8) \
&& (TCL_MINOR_VERSION == 0)))
void
Tcl_SaveResult(Tcl_Interp *interp, Tcl_SavedResult *savedPtr)
{
char *result = Tcl_GetStringResult(interp);
if (interp->freeProc == TCL_STATIC) {
/*
String might go away with another Tcl_Eval() call,
so make a copy.
*/
int length = strlen(result);
savedPtr->result = Tcl_Alloc(length + 1);
strcpy(savedPtr->result, result);
savedPtr->freeProc = TCL_DYNAMIC;
} else {
savedPtr->result = result;
savedPtr->freeProc = interp->freeProc;
/*
We've taken responsibility for savedPtr->result, so make
sure the interp doesn't free it for us.
*/
interp->freeProc = TCL_STATIC;
}
Tcl_ResetResult(interp);
}
void
Tcl_RestoreResult(Tcl_Interp *interp, Tcl_SavedResult *savedPtr)
{
Tcl_SetResult(interp, savedPtr->result, savedPtr->freeProc);
}
void
Tcl_DiscardResult(Tcl_SavedResult *savedPtr)
{
if (savedPtr->freeProc == TCL_DYNAMIC) {
Tcl_Free(savedPtr->result);
} else {
(*savedPtr->freeProc)(savedPtr->result);
}
}
#endifThere! Now you can call Tcl_SaveResult(), Tcl_RestoreResult(), and Tcl_DiscardResult() even if you happen to link against a pre-Tcl 8.1 library.
