EP: 16 - HtDF Interval Data Definition

Part 16. HtDF with Interval Data Definition

We have defined the data definition for an interval, now we will make the function using HtDF recipe

The example asks us to make a function that produces true if the given seat number is an aisle

For reference, look at the interpretation of data definition, it seems that seats 1 and 32 are aisle seats.

Here we make the Signature, Purpose and Stub.

Now we make the tests, When making tests for Intervals, include the first and last value and also the midpoints. Include also test for other points of variance across the interval.

Thanks to the Data definition provided, this helped us to create our test. HtDD and HtDF are related which can help us to design our functions.

And finally, we just copy the template from the Data Definition, make sure you point that out. Comment out the stub and create the code.

The function fulfills the requirements in the problem domain. Data definitions can help us define the templates and the tests.

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Problem Solving using HtDF method

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EP: 18 - HtDF with Itemization

Part 18. HtDF with Itemization From the Countdown Display definition that we have made earlier, we are going to make a function out of it. We have to output an image depending on the state of the countdown. Here is the Signature, Purpose and Stub. It is recommended to run the code often, the earlier we detect bugs, the better. We need some examples. For tests on itemizations, we need to have as many tests as there are cases. Also, if we have an interval, we have to test points of variance. For the Interval, there is not much variance in the seconds before midnight so it is okay to have only one test for that. There is a primitive called text which converts text to an image, we can also use number->string to convert a number into a string datatype. Note that when we are devising tests, we are already working out the behavior of the function before we start coding. Now we get the template and start creating the function body. ...

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EP: 9 - What not to do when designing functions

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