People complain about stack traces, but precisely the point of having stack
traces is that if a pre-condition fails, you don't look at the function
with the pre-condition, you look at the function that was calling it.
Duplicating pre-conditions to callers, as a general pattern, would scale
very badly.
On Thursday, February 19, 2015 at 4:35:54 AM UTC-8, Cecil Westerhof wrote:
>
> I have two different functions for the same functionality. I would like to
> share the pre-conditions between them.
>
> The general function is:
> (defn test-lucky-numbers-general
> "Performance test of lucky numbers general"
> [fn desc nr]
> {:pre [(>= nr 1)
> (<= nr 7)]}
> (println desc)
> (dotimes [i 25]
> (let [lucky (time (fn 10))]))
> (println)
> (dotimes [i nr]
> (time
> (let [upto (int (Math/pow 10 (inc i)))]
> (printf "With upto %d there are %d lucky numbers\n" upto
> (count (fn upto)))))
> (println)))
>
>
> The functions themselves are:
> (defn test-lucky-numbers
> "Performance test of lucky numbers"
> ([]
> (test-lucky-numbers 6))
> ([nr]
> (test-lucky-numbers-general lucky-numbers "Testing performance
> lucky-numbers" nr)))
> and:
> (defn test-lucky-numbers-3
> "Performance test of lucky numbers (3)"
> ([]
> (test-lucky-numbers-3 6))
> ([nr]
> (test-lucky-numbers-general lucky-numbers-3 "Testing performance
> lucky-numbers-3" nr)))
>
>
> And to call all test functions I have:
> (defn test-lucky-numbers-all
> "Test all lucky number performance"
> ([]
> (test-lucky-numbers-all 6))
> ([nr]
> (test-lucky-numbers nr)
> (test-lucky-numbers-3 nr)))
>
>
> When I call a function with the wrong parameter, I get an error from
> test-lucky-numbers-general, but I need it from the calling function. I
> could copy the pre-condition to all functions, but that is not really DRY.
> Is there a way I can share the pre-conditions with all (at this moment)
> four functions?
>
>
> The first dotimes in test-lucky-numbers-general is to warm-up the JVM. Is
> there a way to know if this is already done for the function that is given?
> Then it could be done only when necessary.
>
> --
> Cecil Westerhof
>
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