From: Run Paint Run Run <redmine@...>
Date: 2009-08-02T07:35:50+09:00
Subject: [ruby-core:24677] [Bug #1858] Random#int's Handling of Invalid Arguments Contradicts its Documentation

Bug #1858: Random#int's Handling of Invalid Arguments Contradicts its Documentation
http://redmine.ruby-lang.org/issues/show/1858

Author: Run Paint Run Run
Status: Open, Priority: Normal
Category: core
ruby -v: ruby 1.9.2dev (2009-08-01 trunk 24343) [i686-linux]

The documentation for Random#int claims that it will raise an ArgumentError when the argument is 0 or negative. In fact, 0 causes repeated generation of 0, and for negative numbers the sign appears to be ignored.

  >> prng = Random.new(2)
  => #<Random:0x96a4628>
  >> 20.times.map { prng.int(0) }
  => [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

  >> prng = Random.new(2)
  => #<Random:0x941888c>
  >> 20.times.map { prng.int(-4) }
  => [0, 3, 1, 0, 2, 3, 2, 3, 0, 3, 2, 1, 3, 3, 1, 3, 3, 3, 2, 0]

Could this contradiction be addressed?

Further, I'd suggest that Random.new.int(1) also raises an ArgumentError as it's meaningless to generate a pseudo-random integer between 0 and 1.


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