Created
June 10, 2011 09:56
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Greg Young's Probability Kata
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Value objects are an important concept in DDD. This kata is made both to learn value objects and to learn better ways of testing. | |
Write a probability value object. It should contain the following methods: | |
Probability CombinedWith(Probability) | |
Probability InverseOf() | |
Probability Either(Probability) | |
if you forget your probability math: | |
Either:P(A) + P(B) - P(A)P(B) | |
CombinedWith: P(A)P(B) | |
InverseOf: 1 - P(A) | |
The math is surprisingly not the main part of the exercise. | |
The internal state should be held as a decimal. Use TDD when writing this object. | |
One last thing. You can't put any getters on the object. What's the first test to write? | |
When finished continue reading: https://gist.github.com/1018566 |
You are correct. Updated.
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Shouldn't
Probability InverseOf(Probability)
be
Probability InverseOf()
or do you intend it to be static?