Next: , Previous: C++ Sequence, Up: C++ mappings


6.2.10 Mapping for port types

Simple ports map onto a pure virtual struct providing a data() and read() or write() methods. The data() method takes no parameter and returns a constant reference on the current port data. Input ports may refresh their data by invoking the read() method, while output ports may publish new data by invoking the write() method. Both read() and write() return no value (void).

Ports defined with the multiple flag map onto a similar pure virtual struct, with the difference that data(), read() and write() methods take an additional string (const char *) parameter representing the port element name. Multiple output ports have two additional open() and close() members (also accepting a single string parameter) that dynamically create or destroy ports.

All these method may throw a genom::exception representing an error code.

For instance, the following IDL:

      port in double in_port;
      port multiple in double multi_in_port;
      port out double out_port;
      port multiple out double multi_out_port;

would map into

      struct in_port {
         virtual const double &data(void) const = 0;
         virtual void read(void) = 0;
      };

      struct multi_in_port {
         virtual const double &data(const char *id) const = 0;
         virtual void read(const char *id) = 0;
      };

      struct out_port {
         virtual double &data(void) const = 0;
         virtual void write(void) = 0;
      };

      struct multi_out_port {
         virtual double &data(const char *id) const = 0;
         virtual void write(const char *id) = 0;
         virtual void open(const char *id) = 0;
         virtual void close(const char *id) = 0;
      };