feat(wire): adds std::functional to slave callback functions

Author: SuGlider

libraries/Wire/src/Wire.cpp

@@ -48,7 +48,7 @@ TwoWire::TwoWire(uint8_t bus_num)
 #endif
 #if SOC_I2C_SUPPORT_SLAVE
     ,
-    is_slave(false), user_onRequest(NULL), user_onReceive(NULL)
+    is_slave(false), user_onRequest(nullptr), user_onReceive(nullptr)
 #endif /* SOC_I2C_SUPPORT_SLAVE */
 {
 }
@@ -596,14 +596,14 @@ void TwoWire::flush() {
   //i2cFlush(num); // cleanup
 }
 
-void TwoWire::onReceive(void (*function)(int)) {
+void TwoWire::onReceive(user_onReceive_t function) {
 #if SOC_I2C_SUPPORT_SLAVE
   user_onReceive = function;
 #endif
 }
 
 // sets function called on slave read
-void TwoWire::onRequest(void (*function)(void)) {
+void TwoWire::onRequest(user_onRequest_t function) {
 #if SOC_I2C_SUPPORT_SLAVE
   user_onRequest = function;
 #endif

libraries/Wire/src/Wire.h

@@ -48,10 +48,6 @@
 #ifndef I2C_BUFFER_LENGTH
 #define I2C_BUFFER_LENGTH 128  // Default size, if none is set using Wire::setBuffersize(size_t)
 #endif
-#if SOC_I2C_SUPPORT_SLAVE
-typedef void (*user_onRequest)(void);
-typedef void (*user_onReceive)(uint8_t *, int);
-#endif /* SOC_I2C_SUPPORT_SLAVE */
 
 class TwoWire : public HardwareI2C {
 protected:
@@ -77,8 +73,11 @@ class TwoWire : public HardwareI2C {
 private:
 #if SOC_I2C_SUPPORT_SLAVE
   bool is_slave;
-  void (*user_onRequest)(void);
-  void (*user_onReceive)(int);
+  // functional pointers for user callbacks
+  using user_onRequest_t = void (*)(void);
+  using user_onReceive_t = void (*)(int);
+  user_onRequest_t user_onRequest;
+  user_onReceive_t user_onReceive;
   static void onRequestService(uint8_t, void *);
   static void onReceiveService(uint8_t, uint8_t *, size_t, bool, void *);
 #endif /* SOC_I2C_SUPPORT_SLAVE */
@@ -116,8 +115,8 @@ class TwoWire : public HardwareI2C {
   size_t requestFrom(uint8_t address, size_t len, bool stopBit) override;
   size_t requestFrom(uint8_t address, size_t len) override;
 
-  void onReceive(void (*)(int)) override;
-  void onRequest(void (*)(void)) override;
+  void onReceive(user_onReceive_t) override;
+  void onRequest(user_onRequest_t) override;
 
   //call setPins() first, so that begin() can be called without arguments from libraries
   bool setPins(int sda, int scl);