define an empty constructor and overload DHT::begin

[edWin-m]

The use of an empty constructor allows for some more complex and flexible initialization logic without the need to write out every step explicitly.

[caternuson]

Can you provide more information on why this is necessary? What's an example use case that requires this empty constructor?

[edWin-m]

@caternuson An empty constructor will allow users to define an instance of DHT as a member of their classes. Furthermore, it grants users more options on how and at what stage of their program logic they can set the library config.

Use Case One

DHT dht;

void setup()
{
    dht.begin(D7, DHT11);
}

void loop()
{
    ...
    float humidity = dht.readHumidity();
    ...
}

Use Case Two

class MySensor {
public:
    MySensor();
    MySensor(uint8_t pin);
    void begin();
    void begin(uint8_t pin);
    ...
private:
    ...
    DHT dht;
    ...
};

Use Case Three

• my_sensor.h

void my_sensor_loop();
void my_sensor_setup(uint8_t data_pin, sensor_callback_t cb_func);

• my_sensor.cpp

...
static DHT sg_dht;
...

void my_sensor_setup(uint8_t data_pin, sensor_callback_t cb_func)
{
    ...
    sg_callback = cb_func;
    sg_dht.begin(data_pin, DHT11);
    ...
}

void my_sensor_loop()
{
    ...
    float humidity = sg_dht.readHumidity();
    float temperature = sg_dht.readTemperature();
    ...
}