Tools.h++ Manual

13-4 104011 Tandem Computers Incorporated

13.3 Types of templates

Intrusive lists

For a collection of type T, intrusive lists are lists where type T inherits directly

from the link type itself

. The results are optimal in space and time, but

require you to honor the inheritance hierarchy.

Value-based collections

Value-based collections copy the object in and out of the collection. A very

familiar example of a value-based "collection" is the C array:

int v[100]; /* A 100 element array of ints */

int i = 7;

v[2] = i;

The statement "

v[2] = i

" copies the value of

into the array at index 2. What

resides within the array is a distinct copy, separate from the original object

Value-based collections can contain more complicated objects too. Here's an

example of a vector of

RWCStrings

/* A 100 element array of RWCStrings: */

RWTValVector<RWCString> v(100);

RWCString s("A string");

v[2] = s;

Just as with the array of ints, the statement "

v[2] = s

" copies the value of

into the vector at index 2. The object that lies within the vector is distinct and

separate from the original object

1. See Stroustrup, The C++ Programming Language, Second Edition, Addison-Westley, 1991, for a description

of intrusive lists.