Software Design Exercise

Demonstrating Software Design Skills

This lab explores the fundamentals of software design, and provides an outline for working towards a knowledge claim against the software design skill.

Defining the problem

In order to plan our program, we must first understand the problem that is being addressed. For this lab, the problem is defined as follows:

A program is needed that processes temperature data from a CSV file. The file contains two columns: temperature values and their respective units ('Celsius', 'Fahrenheit', or 'Kelvin'). The program must provide a means read this data into memory, while also providing an interface that allows the programmer to convert and access the values stored in memory using any of the three supported units. For example, if one had 25.0 Celsius stored in an object named `TemperatureReading`, one should be able to access the temperature reading in Fahrenheit using something like `TemperatureReading.Fahrenheit()`, getting a return value of 77.0. The program must also provide a means to write the data back into a CSV file, using one of the defined temperature units for all readings.

From this definition, we can see that we require a way to convert between Kelvin, Fahrenheit, and Celsius. The following equations may prove useful in this endeavour:

• Celsius to Fahrenheit: \(F = (C \times \frac{9}{5}) + 32\)
• Celsius to Kelvin: \(K = C + 273.15\)
• Fahrenheit to Celsius: \(C = (F - 32) \times \frac{5}{9}\)
• Fahrenheit to Kelvin: \(K = (F - 32) \times \frac{5}{9} + 273.15\)
• Kelvin to Celsius: \(C = K - 273.15\)
• Kelvin to Fahrenheit: \(F = (K - 273.15) \times \frac{9}{5} + 32\)

For this lab it is assumed that you are creating a software design document. The exercises will therefore guide you through producing the elements required within said document.

Defining the Structures and Classes

Using the problem definition above, we can now define the datastructures and Classes required to implement the program.

The TemperatureReading Class

Given that we have data readings that may need converting on the fly whenever they are accessed, it makes sense to create a TemperatureReading object that provides methods that implement the conversion equations provided in the previous section.

Logically, the user should not need to know which unit the temperature reading was actually stored using, and should instead be able to simply request a given unit when accessing the data. This means our TemperatureReading object will require three methods besides the __init__() method:

• TemperatureReading.Celsius(): Returns the stored temperature in Celsius.
• TemperatureReading.Fahrenheit(): Returns the stored temperature in Fahrenheit.
• TemperatureReading.Kelvin(): Returns the stored temperature in Kelvin.

The class will also require two properties to store the reading and it’s unit:

• TemperatureReading.value: The temperature reading (float).
• TemperatureReading.unit: The unit that the reading was taken using (string).

The List of Temperatures

The problem also states that the program will need to read several temperatures from a CSV file. This implies that we will require a list of TemperatureReading objects.

Creating the Flowcharts

Now that all data structures and classes have been defined, we can move on to defining the functions and code flow. There are 5 key functions that must be defined here: The three TemperatureReading methods, a function to enable importing of the CSV data, and a function to enable exporting of the CSV data.

As we have not covered CSV file access in lectures yet, these last two function flowcharts are provided for you in .

Submitting the Design

Once the design document is complete, you can generate a PDF and upload it to Mahara to claim the skill.

Application Level Claims

The work so far is designed to support a claim of the software design skill at Knowledge level. In this section, I provide an outline for an expansion on the work so far that will make it possible to claim the skill at application level.