Tools.h++ Manual

16-6 104011 Tandem Computers Incorporated
16
However, you do not have to know these details until you write your own
class RWCollectable class, something we will do in the following chapter.
However, at this point, you should note that when Smalltalk-like collection
classes are restored they necessarily do not know the types of objects they will
be restoring. Hence, they must allocate them off the heap. This means that
you are responsible for deleting the restored contents. This happened in line 11
of the example.
16.3 Summary
In the example in the previous section we saw the use of two operators for
storage and retrieval, respectively, into virtual streams:
RWvostream& operator<<(RWvostream&, const
RWCollectable&); // 1
RWvistream& operator>>(RWvistream&,
RWCollectable&); // 2
There are two similar operators for storage and retrieval into RWFile ’s:
RWFile& operator<<(RWFile&, const
RWCollectable&); // 3
RWFile& operator>>(RWFile&,
RWCollectable&); // 4
In addition to these operators, there are also two operators for storage of
pointers to RWCollectables . These operators have nearly identical
semantics to their “const reference” counterparts (functions 1 and 3,
respectively). The only difference is that they can detect and restore nil
pointers.
RWvostream& operator<<(RWvostream&, const
RWCollectable*); // 5
RWFile& operator<<(RWFile&, const
RWCollectable*); // 6