.. include:: <mmlalias.txt>


Exercise Foundation: ``Sensor`` Hierarchy
=========================================

.. contents::
   :local:

Hypothetical
------------

We are an organization that sits on a large pile of software. Sensors,
*temperature* sensors actually, are fundamental in that pile, and
there are many sensor implementations around. All are organized in a
class hierarchy, starting at an abstract base class (an
:doc:`interface </trainings/material/soup/cxx/cxx03/inheritance-oo-design/index>`):

.. literalinclude:: /trainings/material/soup/cxx/cxx-code/sensors-core/sensors/sensor.h
   :caption: :download:`/trainings/material/soup/cxx/cxx-code/sensors-core/sensors/sensor.h`
   :language: c++

Two concrete implementations of such sensors that we will use in the
exercise series in this course are:

* :download:`RandomSensor
  </trainings/material/soup/cxx/cxx-code/sensors-core/sensors/sensor-random.h>`. That sensor yields
  floating point random numbers in a configurable range.
* :download:`ConstantSensor
  </trainings/material/soup/cxx/cxx-code/sensors-core/sensors/sensor-const.h>`. That one always yields the
  same temperature. Cool for testing.

We will extend that hierarchy along with the exercises.
  
Class Hierarchy
---------------

.. plantuml::

   @startuml

   interface Sensor {
     + double get_temperature()
   }
   
   class I2CSensor {
     + double get_value()
   }
   class RandomSensor {
     + double get_value()
   }
   class ConstantSensor {
     + double get_value()
   }
   
   Sensor <|.. I2CSensor
   Sensor <|.. RandomSensor
   Sensor <|.. ConstantSensor

   @enduml