I am trying to understand this code which is from Tcl documentation

typedef int Tcl_DriverOutputProc(
        ClientData instanceData,
        const char *buf,
        int toWrite,
        int *errorCodePtr);

As I know the purpose of typedef is to assign alternative names to existing types, so why is needed to typedef int to function? How this can be used?

c++ c types tcl
Edit
Report