[Newbies] How to shorten a method (using inject: into: ?)

[Randal L. Schwartz]

>>>>> "cdrick" == cdrick  <cdrick65 at gmail.com> writes:

cdrick> Hi Stan,
cdrick> 2008/7/21 stan shepherd <squeak414 at free.fr>:
>> 
>> Hi, I have the following method, that code critics flags as long:
>> 
>> testMaleMeiosis2
>> | testSet mCount pCount mTotal pTotal |
>> pTotal := 0.
>> mTotal := 0.
>> Forecaster testMale meiose
>> do: [:strand |
>> testSet := strand testRun.
>> mCount := testSet maternalCount.
>> pCount := testSet paternalCount.
>> mTotal := mTotal + mCount.
>> pTotal := pTotal + pCount].
>> self
>> should: [mTotal = 100
>> and: [pTotal = 100]]
>> 
>> I'm trying to shorten it, including various attempts with inject: into: ,
>> but with no success. Any tips please?

cdrick> So somethink like that should work:

cdrick> testMaleMeiosis2
cdrick> | resultArray tesSet |
cdrick> testSet := strand testRun.
cdrick> resultArray := Forecaster testMale meiose
cdrick> 	inject: #(0 0)
cdrick>         into: [:array :val |
cdrick>              array at: 1 put: (array at: 1) + testSet maternalCount.
cdrick> 	     array at: 2 put: (array at: 2) + testSet paternalCount.
cdrick> 	     array]

cdrick> self should: [ resultArray = #(100 100)].

This looks even uglier.  How about first gathering the testSets, then
getting what you need from those:

| testSets mTotal pTotal |

testSets := (Forecaster testMale meiose) collect: [:strand | strand testRun ].
mTotal := (testSets collect: [:each | each maternalCount]) sum.
pTotal := (testSets collect: [:each | each paternalCount]) sum.

Unless you're talking about 5000 elements in testSets, this is likely in the
same ballpark for speed, and that's probably dwarfed by the cost of #testRun
anyway.

Sometimes an obsession with #inject:into: as a shiny object leads you down a
dark path.  Especially with sums.  Consider #sum first.

-- 
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
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