Add Importable::symbol.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@2604 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/dl/lib/dl/import.rb

@@ -105,6 +105,29 @@ module DL
 	@types.typealias(*args)
       end
 
+      # example:
+      #  symbol "foo_value"
+      #  symbol "foo_func", "IIP"
+      #
+      def symbol(name, ty = nil)
+	sym = nil
+	@LIBS.each{|lib|
+	  begin
+	    if( ty )
+	      sym = lib[name, ty]
+	    else
+	      sym = lib[name]
+	    end
+	  rescue
+	    next
+	  end
+	}
+	if( !sym )
+	  raise(RuntimeError, "can't find the symbol `#{name}'")
+	end
+	return sym
+      end
+
       # example:
       #   import("get_length", "int", ["void*", "int"])
       #
@@ -116,12 +139,7 @@ module DL
 	ty,enc,dec = encode_types(argtypes)
 	symty = rty + ty
 
-	@LIBS.each{|lib|
-	  begin
-	    sym = lib[name, symty]
-	  rescue
-	    next
-	  end
+	sym = symbol(name, symty)
 
 	mname = name.dup
 	if( ?A <= mname[0] && mname[0] <= ?Z )
@@ -154,8 +172,6 @@ module DL
 	].join("\n")
 
 	return sym
-	}
-	raise(RuntimeError, "can't find #{name}.")
       end
 
       def _args_