Microsoft Word OpenIssuesInOO. doc

Abstraction mechanisms.  In this part it has been argued that composition should be 

supported as well as classification. Aspects of single and multiple inheritance, multiple 

classifications and dynamic classification have been discussed. It has been shown that 

languages with strong support for block structure, part objects and singular objects offer 

certain alternatives to multiple inheritance. There have also been discussions of the pros 

and cons of inner versus super, various alternatives for supporting  parameterised 

classes. issues related to typing including covariance and contravariance, and types 

versus classes. 

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