From: Alexander <madevilgenius@...>
Date: 2005-11-25T11:51:30+09:00
Subject: Re: Improving min/max for Range

On 11/25/05, Yukihiro Matsumoto <matz@ruby-lang.org> wrote:
> |Good point. I think max should throw if the number doesn't support the
> |integer protocol; there's simply no way to handle it intelligently.
> |For int-type types, I suggest that (end.to_int - 1) should be used,
> |since there is no #pred counterpart to #succ.
>
> I've just committed my implementation of Range#min and #max to CVS
> HEAD.  Check if you have interest.
>
>                                                         matz.

I see you decided to return nil instead of throwing; acceptable, I
suppose. More sneaky is how you let Enumerable handle the case when
the end is excluded -- I would have preferred to do that only do if
#end was not an integer.

Here's a unit test patch, btw:

diff -u -r1.5 test_range.rb
--- test/ruby/test_range.rb     5 Aug 2005 23:56:02 -0000       1.5
+++ test/ruby/test_range.rb     25 Nov 2005 02:47:06 -0000
@@ -31,4 +31,24 @@
   def test_duckrange
     assert_equal("bc", "abcd"[DuckRange.new(1,2)])
   end
+
+  def test_min
+    assert_equal(1, (1..2).min)
+    assert_equal(nil, (2..1).min)
+    assert_equal(1, (1...2).min)
+
+    assert_equal(1.0, (1.0..2.0).min)
+    assert_equal(nil, (2.0..1.0).min)
+    assert_equal(1, (1.0...2.0).min)
+  end
+
+  def test_max
+    assert_equal(2, (1..2).max)
+    assert_equal(nil, (2..1).max)
+    assert_equal(1, (1...2).max)
+
+    assert_equal(2.0, (1.0..2.0).max)
+    assert_equal(nil, (2.0..1.0).max)
+    assert_raise(TypeError) { (1.0...2.0).max }
+  end
 end

Alexander.