While cleaning up some code I ran across some obscure code of mine from my Ruby youth. I remembered reading about an ultra cool Ruby tool the other day so I decided to give my code a good flogging. The victim for tonight is a method used to slice ID numbers into chunks of at most 4 characters long. This is required to overcome the typical Linux file system limitation of at most 32000 entries per directory. In this case the project stores roughly a million thumbnail images on disk. We start with the original piece of code:
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def splice_number(number, part_size = 4)
n = number.to_s
r = []
return r if n.size.zero?
(n.size / part_size).times { |t| r << n[(t*part_size)..((t+1)*part_size-1)] }
r << n[-(n.size % part_size)..n.size] if (n.size % part_size) > 0
r
end
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Ah yes, WTF was I thinking when I wrote this? Who cares, it seemed very clever then! What does Flog think about this?
Total score = 28.35
none#splice_number: (28)
7: size
3: *
2: %
2: []
2: <<
1: +
1: -@
1: -
1: /
1: lit_fixnum
1: zero?
1: >
1: to_s
1: times
Pretty good score. Now it’s time for some torturing. Say hello to my little friend: unpack!
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def splice_number(number, part_size = 4)
n = number.to_s
n.unpack("a#{part_size}" * (n.size / part_size) + ((n.size % part_size == 0) ? "" : "a*"))
end
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Flog?
Total score = 13.05
none#splice_number: (13)
3: size
1: %
1: /
1: ==
1: *
1: +
1: to_s
1: unpack
0: lit_fixnum
Yeow, well over half the pain gone!! Perhaps we can still improve by being less clever?
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def splice_number(number, part_size = 4)
n = number.to_s
r = n.unpack("a#{part_size}" * (n.size / part_size) + "a*")
r.delete("")
r
end
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More lines, but less code! Hmm?
Total score = 9.25
none#splice_number: (9)
1: size
1: /
1: *
1: +
1: delete
1: to_s
1: unpack
0: lit_fixnum
Weeh, a full 2/3 of the pain flogged out of the code! That’s all the torture I’ll do for tonight..
Update: Okay, couldn’t help myself, last blow:
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def splice_number(number, part_size = 4)
n = number.to_s
p = "a#{part_size}"
t = n.size / part_size
r = n.unpack(p * t + "a*")
r.delete("")
r
end
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With score:
Total score = 8.05
none#splice_number: (8)
1: *
1: size
1: +
1: delete
1: to_s
1: /
1: unpack
0: lit_fixnum
Done..
