Space-and time-efficient memory layout for multiple inheritance

摘要

Traditional Impelmentations of multiple inheritance bring about not only an overhead in terms of run-time but also a significant increse in object space.For example,the number of compiler-generated fields in a certian object cna be as large as quadiratic in the nuber of it ssubodjects.The porblem of effiient object layout is compounded by the need to support two different semantics of multiple inheritance: shared,in which a base class inherited along distinct paths occures only oce in the derived class,and epeated,in which this base has multiple distinct occurrences in the derived.