Q: Refactorizing code because Inheritance and Interfaces

[Michael Erdmann <Michael.Erdmann@snafu.de>]

Dear all,

again i got a problem with inheritance. Lets assume the following
situation, that you have made a nice package reading in xml
files. The specification contains something like this:

    package XML_Reader is .
       type Object is new Sax.... with ... bla...
       procedure X(This : in out Object......)

Some weeks later i have realized that this implemenation is nice, 
but it is part of a generalization:

    package Abtract_Reader is
        type Object is abstract tagged null record;
        type Handle is access all Object'Class;

        procedure X(.... ) is abstract;

In order to line up the implemenation of the XML_Reader with the 
Abstract_Reader interface i need to rewrite the complete XML_Reader.
Is there any way to avoid such situations?


Regards
    M.Erdmann


PS:
In java i would use   constructs as implements  Sax..,Abstract_Reader.