- virtual size_t DoWrite(const void *buffer, size_t size) = 0;
- virtual off_t DoSeekOutput(off_t pos, wxSeekMode mode) = 0;
- virtual off_t DoTellOutput() const = 0;
+ virtual size_t DoWrite( const void *WXUNUSED(buffer), size_t WXUNUSED(size) )
+ { return 0; }
+ virtual off_t DoSeekOutput( off_t WXUNUSED(pos), wxSeekMode WXUNUSED(mode) )
+ { return wxInvalidOffset; }
+ virtual off_t DoTellOutput() const
+ { return wxInvalidOffset; }