Exercises in Programming Style–Abstract Things

Yan Cui

I help clients go faster for less using serverless technologies.

NOTE : read the rest of the series, or check out the source code.

If you enjoy read­ing these exer­cises then please buy Crista’s book to sup­port her work.

exercises-prog-styles-cover

Fol­low­ing on from the last post, we will look at the Abstract Things style today.

 

Style 13 – Abstract Things

Constraints

  • Larger problem is decomposed into abstract things that make sense for the problem domain
  • Each abstract thing is described by what operations the things of that abstraction can do
  • Concrete things are then bound to the abstractions
  • The rest of the application uses the things not by what they are but by what they do in the abstract

 

First, let’s define our abstractions:

Style13_01

Unfortunately, after this point the implementation are basically identical to the Things style (except the relevant members in each type is defined as part of the corresponding abstraction rather than as a member of the type):

Style13_02 Style13_03 Style13_04 Style13_05

Finally, remember we need to “use the things not by what they are but what they do in the abstract”, so call the WordFrequencyController via its abstraction:

Style13_06

 

You can find the source code for this exer­cise here.

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