It looks like mine is more complete, with data inheritance, inclusion of external files (which allows explicit loading of functionality into selected objects), and the ability to delete fields or methods.

At least from the README; I haven't been able to get a copy of it from CPAN yet.

update: I finally found a copy; it's efficient but doesn't provide for inheritance or data fields; mine is much more complete. And just as fast, as far as I can tell. I also benchmarked against Class::Classless; my code is quite a bit faster (168x as fast for inherited subroutine calls, 20+ times as fast for field access!):

empty subroutine calls
                 Rate  Classless SelfMethods Prototyped      Object Pl
+ainOleData
Classless      4225/s         --        -95%       -99%        -99%   
+      -99%
SelfMethods   90540/s      2043%          --       -84%        -84%   
+      -85%
Prototyped   577873/s     13578%        538%         --         -1%   
+       -2%
Object       582772/s     13694%        544%         1%          --   
+       -1%
PlainOleData 587346/s     13802%        549%         2%          1%   
+        --

empty inherited subroutine calls
               Rate  Classless Prototyped     Object
Classless    3370/s         --       -99%       -99%
Prototyped 568592/s     16772%         --        -1%
Object     572334/s     16883%         1%         --

field reading
                 Rate    Classless  SelfMethods   Prototyped PlainOleD
+ata
Classless      3969/s           --         -88%         -95%         -
+98%
SelfMethods   34115/s         760%           --         -54%         -
+84%
Prototyped    74488/s        1777%         118%           --         -
+64%
PlainOleData 209199/s        5171%         513%         181%          
+ --

field writing
                 Rate    Classless  SelfMethods   Prototyped PlainOleD
+ata
Classless      3760/s           --         -92%         -96%         -
+98%
SelfMethods   47737/s        1170%           --         -44%         -
+74%
Prototyped    85151/s        2165%          78%           --         -
+54%
PlainOleData 184470/s        4806%         286%         117%          
+ --

inherited field reading
              Rate  Classless Prototyped
Classless   3268/s         --       -96%
Prototyped 73604/s      2152%         --

inherited field writing
              Rate  Classless Prototyped
Classless   3231/s         --       -96%
Prototyped 85301/s      2540%         --
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