Hi Max, Interesting results... replacing the #yourself in newSum: cuts the runtime by a factor of two. using an [:x | x ] block cost 10% compared to a direct version of sum. So the fastest sum is: sum ^ self inject: (self ifEmpty: [ ^ 0 ] ifNotEmpty: [ self anyOne ]) into: [ :sum :each | sum + each ] And sum ^ self sum: [:x | x ] is 10% slower. And sum ^ self sum: #yourself is 100% slower (i.e. x2) It may be wise to avoid using #yourself for a block. Thierry 2015-12-01 9:17 GMT+01:00 Max Leske <maxleske@gmail.com>:
Hi guys,
Collection defines #sum:, #detectSum: and #sumNumbers:, all of which accomplish the same (in principal) but with subtle differences:
#sum: - uses #inject:into: with #anyOne as the injected element and will thus fail for empty collections
#detectSum: - uses ânextValue + sumâ instead of âsum + nextValueâ which makes it a lot slower when dealing with large numbers (primitive fails and number conversion is necessary)
#sumNumbers: - same as #sum but doesnât fail for empty collections. Only good for numbers though.
Benchmarks:
[ 100 timesRepeat: [ (1 to: 1000000) sum: #yourself ] ] timeToRun 18062 [ 100 timesRepeat: [ (1 to: 1000000) detectSum: #yourself ] ] timeToRun 42391 [ 100 timesRepeat: [ (1 to: 1000000) sumNumbers: #yourself ] ] timeToRun 18096
Can we settle for a single implementation? Such as (modified from #sumNumbers:):
newSum: aBlock ^ self inject: (self ifEmpty: [ 0 ] ifNotEmpty: [ self anyOne ]) into: [ :sum :each | sum + (aBlock value: each) ]
This implementation combines the best of the three implementations I think. Benchmark:
[ 100 timesRepeat: [ (1 to: 1000000) newSum: #yourself ] ] timeToRun 17955
BTW, there is also the message #sum, which suffers from the same problem as #sum: (the implementation is basically a copy). #sum could be implemented as
sum ^ self sum: [ :x | x ]
As for the name for the new method, I suggest #sum:.
Cheers, Max