virtual std::string midi_option () const = 0;
/* State Control */
-
- /* non-virtual method to avoid possible overrides of default
- * parameters. See Scott Meyers or other books on C++ to
- * understand this pattern, or possibly just this:
- *
- * http://stackoverflow.com/questions/12139786/good-pratice-default-arguments-for-pure-virtual-method
- */
- int start (bool for_latency_measurement=false) {
- return _start (for_latency_measurement);
- }
-
+
/** Start using the device named in the most recent call
* to set_device(), with the parameters set by various
* the most recent calls to set_sample_rate() etc. etc.
* any existing systemic latency settings.
*
* Return zero if successful, negative values otherwise.
- */
- virtual int _start (bool for_latency_measurement) = 0;
+ *
+ *
+ *
+ *
+ * Why is this non-virtual but ::_start() is virtual ?
+ * Virtual methods with default parameters create possible ambiguity
+ * because a derived class may implement the same method with a different
+ * type or value of default parameter.
+ *
+ * So we make this non-virtual method to avoid possible overrides of
+ * default parameters. See Scott Meyers or other books on C++ to understand
+ * this pattern, or possibly just this:
+ *
+ * http://stackoverflow.com/questions/12139786/good-pratice-default-arguments-for-pure-virtual-method
+ */
+ int start (bool for_latency_measurement=false) {
+ return _start (for_latency_measurement);
+ }
/** Stop using the device currently in use.
*
protected:
AudioEngine& engine;
+
+ virtual int _start (bool for_latency_measurement) = 0;
};
struct AudioBackendInfo {