Object-Oriented Programming Part-2
==================================

.. toctree::
   :maxdepth: 1


Indices and tables
------------------

* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`


Introduction
------------

In the last topic, we defined a base class for batteries. Using inheritance, we can create different types of batteries, and specialize the characteristics of the base class battery to match.


.. _section_heading-KR6_Battery:

KR6_Battery
-----------
The KR6 battery type is AA sized and uses NiCD chemistry. We can specialize the Battery base class for the KR6 battery as
follows:

* Derive a new class from the Battery base class
* Reimplement the class variables with KR6 specific values
* Reimplement the ``get_voltage()`` method with KR6 specific formula

.. literalinclude:: BatteryOrigPkg/KR6.py
   :linenos:

For very little work, we were able to create a new battery that took advantage of previously created logic for all but 5 of the class attributes. :numref:`figure-battery_class_diagram` represents the class diagram of the KR6 class that has been created:

.. _figure-kr6_class_diagram:

.. figure:: BatteryOrigPkg/kr6_class_diagram.png
   :scale: 80 %
   :align: center

   KR6 Class Diagram



And we can see the fruits of our labor, a customized battery type!

>>> #
>>> # Import the battery type
>>> #
>>> from BatteryOrigPkg.KR6 import KR6
>>> #
>>> # Create a KR6 battery
>>> #
batt0 = KR6("K7811")
>>> #
>>> # Get the eval'able form
>>> #
>>> repr(batt0)
'KR6("K7811", 0)'
>>> #
>>> # Get the human readable form
>>> #
>>> print(batt0)
0.9v (Charge:0% Size:AA Type:NiCd SN:"K7811")
>>> #
>>> # Change it's charge level
>>> #
>>> batt0.set_percent_charged(50)
>>> print(batt0)
1.05v (Charge:50% Size:AA Type:NiCd SN:"K7811")
>>> batt0.set_percent_charged(100)
>>> print(batt0)
1.2v (Charge:100% Size:AA Type:NiCd SN:"K7811")




.. _section_heading-HR14_Battery:

HR14_Battery
------------

The HR14 battery type is C sized and uses NiMH chemistry.
For this battery, we use an exponential curve to represent the discharge curve, which is easily handled using a customized ``get_voltage()`` method.

.. literalinclude:: BatteryOrigPkg/HR14.py
   :linenos:

Taking the HR14 battery for a spin...

>>> #
>>> # Import the battery type
>>> #
>>> from BatteryOrigPkg.HR14 import HR14
>>> #
>>> # Create a HR14 battery
>>> #
batt1 = HR14("AF4194", 35)
>>> #
>>> # Get the eval'able form
>>> #
>>> repr(batt1)
'HR14("AF4194", 35)'
>>> #
>>> # Get the human readable form
>>> #
>>> print(batt1)
1.0244985104v (Charge:35% Size:C Type:NiMH SN:"AF4194")
>>> #
>>> # Change it's charge level
>>> #
>>> batt1.set_percent_charged(50)
>>> print(batt1)
1.04999696v (Charge:50% Size:C Type:NiMH SN:"AF4194")
>>> batt1.set_percent_charged(100)
>>> print(batt1)
1.19998784v (Charge:100% Size:C Type:NiMH SN:"AF4194")



.. _section_heading-LR4_Battery:

LR4_Battery
-----------

The LR4 battery type is AA sized using Alkaline chemistry. For this battery, the conversion from charge to voltage is based on a piecewise curve. Again, this is easily handled using a customized ``get_voltage()`` method.

.. literalinclude:: BatteryOrigPkg/LR4.py
   :linenos:

Taking the LR4 battery for a spin...

>>> #
>>> # Import the battery type
>>> #
>>> from BatteryOrigPkg.LR4 import LR4
>>> #
>>> # Create a LR4 battery
>>> #
batt2 = LR4("GK245-01", 25)
>>> #
>>> # Get the eval'able form
>>> #
>>> repr(batt2)
'LR4("GK245-01", 25)'
>>> #
>>> # Get the human readable form
>>> #
>>> print(batt2)
1.042v (Charge:25% Size:AA Type:Alkaline SN:"GK245-01")
>>> #
>>> # Change it's charge level
>>> #
>>> batt2.set_percent_charged(50)
>>> print(batt2)
1.124v (Charge:50% Size:AA Type:Alkaline SN:"GK245-01")
>>> batt2.set_percent_charged(100)
>>> print(batt2)
1.49v (Charge:100% Size:AA Type:Alkaline SN:"GK245-01")


.. _section_heading-Playing_With_Batteries:

Playing with Batteries
----------------------

Above, we created 3 batteries (one for each type). Lets try out the various operations on them:

>>> #
>>> # Getting properties of the battery
>>> #
>>> batt0.get_num_created()
3
>>> # Remember, the instance counter is
>>> # on the base class and was never
>>> # reimplemented, so, '3' makes sense.
>>> # because we made 3 batteries.
>>> #
>>> batt0.get_form_factor()
'AA'
>>> batt0.get_chemistry()
'NiCd'
>>> batt0.get_serial_numer()
'K7811;
>>> batt0.get_percent_charged()
100
>>> batt0.get_voltage()
1.2
>>> batt1.get_voltage()
1.1998784
>>> batt2.get_voltage()
1.49
>>> #
>>> # Comparison Operations
>>> #
>>> batt0 == batt1
False
>>> batt0 != batt1
True
>>> batt0 <= batt1
False
>>> batt0 < batt1
False
>>> batt0 >= batt1
True
>>> batt0 > batt1
True
>>> #
>>> # Numerical Operations
>>> #
>>> batt0 + batt1
2.3999878399999997
>>> batt0 - batt2
-0.29000000000000004
>>> int(batt0)
1
>>> float(batt0)
1.2