Screenplay: C++: Inheritance, Interfaces, virtual

  • start with concrete spi thermometer, thermometer.h (this is the first that we need)

    • main program spi.cc which reads temperature and writes it to output.

  • hmm. i2c. duplicate code

    • two classes (spi and i2c) in thermometer.h

    • two exes likewise

  • discuss: unrelated classes. similar (get_temperature()), but unrelated.

  • proof of missing relationship: “algorithm”: read temperatures in a loop, and give histogram

  • algorithm inline in spi.cc

  • extract as function (still in spi.cc)

  • hmm. and i2c?

  • duplicate code into i2c.cc

  • hmm. like thermometer.h, collect histogram routines in histogram.{h,cc}. modify mains accordingly.

  • hmm. look in histogram.{h,cc} and thermometer.{h,cc}.

  • discuss. I want only one routine make_histogram() that makes me a histogram from any thermometer.

  • histogram.{h,cc}: collapse into one, Thermometer. without pointer, for the time being.

  • thermometer.h: base class … interface

  • discuss very thoroughly

    • dynamic dispatch

    • runtime overhead (as opposed to copied code, like before we had a base class)

  • discuss: mock