Tools.h++ Manual

104011 Tandem Computers Incorporated 13-3

want to declare a

BaseVector

class that holds the length of any vector. We

would then derive the template-based vectors Vector from this. Of course, the

code required to return the length of a vector is trivial, and so it turns out that

in practice it isn't worth doing this.

Factoring out commonality

For a more substantial example, take a look at the intrusive linked-list class

RWTIsvSlist<T>

. This is a linked list of types

which are required to inherit

from class

RWIsvSlink

. This class contains a "next" ﬁeld, consisting of a

pointer to the next link. A few moments reﬂection will convince you that we

don't really need to know the derived type of the link to actually walk the list.

We need only know that it inherits from

RWIsvSlink

. Furthermore, given an

existing link, we don't even need to know its type to add or remove it from the

list!

Hence, all this code can be factored out, compiled once, and forgotten.

13.2 Naming scheme

All of the template class names start with "RWT", followed by a three letter

code:

Isv

Intrusive lists

Val

Value-based

Ptr

Pointer-based

Hence,

RWTValOrderedVector<T>

is a value-based template for an ordered

vector of type