added error/exception classes for better handling

lib/X11.rb

@@ -10,4 +10,7 @@ module X11
   # of 4 bytes. For instance, C<pack(padded('Hello'), 'Hello')> gives
   # C<"Hello\0\0\0">.
   def self.pad(x);  x + "\0"*(-x.length & 3); end
+
+  class X11Error < StandardError; end
+  class X11Exception < RuntimeException; end
 end

lib/X11/display.rb

@@ -1,4 +1,15 @@
 module X11
+
+  class DisplayException < X11Exception; end
+  class ConnectionException < DisplayException; end
+  class AuthorizationException < ConnectionException
+    attr_reader :errorcode
+    def initialize msg, errcode=nil
+      super msg
+      @errorcode = errcode
+    end
+  end
+
   class Display
 
     # Open a connection to the specified display (numbered from 0) on the specified host
@@ -49,13 +60,13 @@ private
           len, major, minor, xlen = @socket.read(7).unpack("CSSS")
           reason = @socket.read(xlen * 4)
           reason = reason[0..len] 
-          raise "Connection to server failed -- (version #{major}.#{minor}) #{reason}"
+          raise AuthorizationException.new "Connection to server failed -- (version #{major}.#{minor}) #{reason}", X11::Auth::FAILED
         when X11::Auth::AUTHENTICATE
-          raise "Connection requires authentication"
+          raise AuthorizationException.new "Connection requires authentication", X11::Auth::AUTHENTICATE
         when X11::Auth::SUCCESS
           raise "fix me"
         else
-          raise "received unknown opcode #{type}"
+          raise AuthorizationException.new "Received unknown opcode #{type}" 
       end
     end
   end

lib/X11/protocol.rb

@@ -1,4 +1,8 @@
 module X11
+
+  class ProtocolError < X11Error; end
+  class ByteOrderError < ProtocolError; end
+
   class Protocol
 
     # endiness of your machine
@@ -8,7 +12,7 @@ module X11
       when "\1\0\0\0"
         "l"
       else
-        raise "Cannot determine byte order"
+        raise ByteOrderError.new "Cannot determine byte order"
     end
 
     MAJOR = 11