From: Marc-Andre Lafortune <redmine@...>
Date: 2010-03-02T16:52:31+09:00
Subject: [ruby-core:28399] [Bug #2495] Matrix: Vector#each2 should check its argument

Issue #2495 has been updated by Marc-Andre Lafortune.



Hi,

On Mon, Feb 1, 2010 at 10:44 PM, Yusuke ENDOH <mame@tsg.ne.jp> wrote:
> Matz or Keiju, will you give us your opinion?

Ist Keiju is even registered on the ruby-core mailing list?


I'd like to point out an alternate implementation can use #each instead of #[], and at least avoid the non-sensical results on integers. Example:

diff --git a/lib/matrix.rb b/lib/matrix.rb
index d452bf4..f9b2f58 100644
--- a/lib/matrix.rb
+++ b/lib/matrix.rb
@@ -1146,8 +1146,10 @@ class Vector
   def each2(v) # :yield: e1, e2
     Vector.Raise ErrDimensionMismatch if size != v.size
     return to_enum(:each2, v) unless block_given?
-    size.times do |i|
-      yield @elements[i], v[i]
+    i = 0
+    v.each do |elem|
+      yield @elements[i], elem
+      i+=1
     end
     self
   end


I'm all for duck typing, as long as we give an idea of what type of "quacking" we're expecting. I would still suggest adding at the beginning of the method:

unless v.respond_to?(:size) && v.respond_to?(:each)
  raise TypeError, "Argument must respond to :size and :each"
end

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