5 years, 6 months ago.

The issue you are referencing with _putc() is that it is defined in Stream.h as pure virtual:

virtual int _putc(int c) = 0;

The =0, means you must implement this yourself, there is no implementation in Stream class. This is because there is no way for Stream to know where you want to actually putc the characters.

The only reason for LCD to inherit from Stream is if you really need/want to use the full Stream interface with all the fancy methods (read, write, seek, rewind, printf, etc, etc).

I would be immediately wary of trying to implement the Stream interface. There is a lot going on here and it is probably more complicated than what you need. Stream inherits from both FileLike and NonCopyable which themselves inherit from additional classes. Stream is just an interface and if you want to use it you are going to have to go through and implement the virtual functions for your class so it is compatible with the Stream interface. It is possible all you have to do is implement _putc() and _getc() - I don’t know I’ve never tried. Looks like you also need to provide the char buffer for Stream in the ctor.

I would get started by having a send() method inside class LCD that just accepts a regular char buffer. Easy.

class LcdDisplay{
public:
    LcdDisplay(I2C& i2c) :
        _i2c(i2c),
        _address(0) {
    }
    
    // put string on LCD
    void send(char* buffer) {
        // Do stuff to put buffer on I2C bus
    }

private:
    I2C& _i2c;
    uint8_t _address;
};

Also, I was getting some weird compile errors around naming. Class name LCD_I2C did not work.