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This coding exercise comes from Upcase, the online learning platform we run. It's part of the Refactoring course and is just one small sample of all the great material available on Upcase, so be sure to visit and check out the rest.
In this exercise, you'll use the Null Object pattern to encapsulate conditional logic relating to nil. The conditions in this exercise are more complex than the ones in the first exercise. You may want to use more than one Null Object class.
Watch a relevant example from The Weekly Iteration.
To start, you'll want to clone and run the setup script for the repo
git clone git@github.com:thoughtbot-upcase-exercises/null-object-part-two.git
cd null-object-part-two
bin/setup
- Open
lib/user.rbin your favorite editor. - Look for conditionals related to
nil. - Introduce a Null Object. Think of a good name based on what
nilrepresents in this context. - Replace a single conditional by moving the nil logic to the Null Object.
- Repeat step four until nothing else can be moved to the Null Object.
- Repeat steps three through five until the
nillogic is entirely encapsulated within Null Objects. - Make sure all tests pass by running
rake.
Check out the featured solution branch to see the approach we recommend for this exercise.
If you find yourself stuck, be sure to check out the associated Upcase Forum discussion for this exercise to see what other folks have said.
When you've finished the exercise, head on back to the Refactoring course to find the next exercise, or explore any of the other great content on Upcase.
null-object-part-two is Copyright © 2015-2018 thoughtbot, inc. It is free software, and may be redistributed under the terms specified in the LICENSE file.
This exercise is maintained and funded by thoughtbot, inc.
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