[BUG] Weird behaviour from * (splat) operator when passed to a method.
Reported by Nikos Dimitrakopoulos | April 15th, 2008 @ 11:24 AM | in 1.0 preview
First of all my apologies for two things:
a) for using a more clear example
b) for pasting so much info here
require 'enumerator'
p1,p2 = (0..4).to_a.sort_by{rand}, (0..4).to_a.sort_by{rand}
nb = Array.new(p1.size){[]}
(p1 + p1[0..1]).each_cons(3){|l,m,r| nb[m] += [l,r] }
(p2 + p2[0..1]).each_cons(3){|l,m,r| nb[m] += [l,r] }
nb.map{ |*args| p *args; p args.shift; p *args }
Here are the results from different ruby implementations:
MRI:
[3, 1, 1, 4]
[3, 1, 1, 4]
[0, 4, 3, 0]
[0, 4, 3, 0]
[4, 3, 4, 3]
[4, 3, 4, 3]
...
=> [nil, nil, nil, nil, nil]
Ruby1.9:
[3, 2, 4, 3]
[3, 2, 4, 3]
[2, 4, 2, 4]
[2, 4, 2, 4]
[0, 1, 3, 1]
[0, 1, 3, 1]
...
=> [nil, nil, nil, nil, nil]
JRuby 1.1:
[2, 4, 4, 3]
[2, 4, 4, 3]
[3, 2, 2, 4]
[3, 2, 2, 4]
[1, 0, 3, 1]
[1, 0, 3, 1]
...
=> [nil, nil, nil, nil, nil]
Rubinius:
[1, 2, 2, 1]
[1, 2, 2, 1]
nil
[4, 0, 0, 3]
[4, 0, 0, 3]
nil
[0, 3, 4, 0]
[0, 3, 4, 0]
nil
...
=> [nil, nil, nil, nil, nil]
Bug for these examples the behaviour is the same...
Any thoughts would be welcome.
You can also check out #363 to see how I found this and why this can and is a serious problem :) (i will update that ticket soon)
Comments and changes to this ticket
-
Ryan Davis April 29th, 2008 @ 04:57 PM
- → Assigned user changed from “” to “Wilson Bilkovich”
-
-
Nikos Dimitrakopoulos April 30th, 2008 @ 04:24 AM
Since my first report the #p has changed so it doesn't print anything if nil is passed. This fixed this particular example but things don't work always as expected. I'm not sure whether the splat op is the problem or the way the various methods handle nil input...
-
Eero Saynatkari April 30th, 2008 @ 09:59 PM
- → State changed from “new” to “resolved”
There are a lot of weird Ruby semantics, such as the difference between #p and #puts with a nil input. I am closing this for now, please re-open or create a new one if you are able to pinpoint a failing case.
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Wilson Bilkovich