[ruby/prime] Fix Prime.include?

Previously, it would be an infinite loop if passed a non-prime
integer.

Also, Prime.include? should also provide similar results to
Module#include? if passed a Module, so handle that.

For consistency with Enumerable#include?, return false if passed
other object types.

Fixes Ruby Bug 10167.

https://github.com/ruby/prime/commit/55dda6aa7f

1 files changed, 12 insertions, 0 deletions

diff --git a/lib/prime.rb b/lib/prime.rb
index 5be12f24f5..44129d2dd7 100644
--- a/lib/prime.rb
+++ b/lib/prime.rb
@@ -141,6 +141,18 @@ class Prime
     generator.each(&block)
   end
 
+  # Return true if +obj+ is an Integer an is prime.  Also returns
+  # true if +obj+ is a Module that is an ancestor of +Prime+.
+  def include?(obj)
+    case obj
+    when Integer
+      prime?(obj)
+    when Module
+      Module.instance_method(:include?).bind(Prime).call(obj)
+    else
+      false
+    end
+  end
 
   # Returns true if +value+ is a prime number, else returns false.
   #