GCO4020/CSC428 - Advanced Object Oriented Techniques In C++
Reference material

GCO4020/CSC428
Glossary

Accessor Function

A public member function which provides the means to modify or retrieve the value of one or more non-public data members of a class (often a container class¤).

Cloneable class

A class with a virtual clone() member which returns a dynamically allocated copy of the original object. Such classes can be manipulated polymorphically, yet still pass on underlying type information to new objects. Sometimes used to implement a simple form of virtual constructor¤.

Closure

A function which has access to local variables from the scope in which it is defined. Normal C++ functions cannot be closures¤ (since they may only be defined at global scope), but non-static member functions of local classes (which may be declared in local scopes) can act as closures¤ if correctly set up to do so.

Container class

A class (or more commonly a templated class) used to store a collection of values in some useful data structure.

Encapsulation

The principle and practice of restricting access to the internal workings of a class (typically all of its data members and any function members which implement internally controlled operations). In C++ the protected and private members of a class are encapsulated.

Factory class

A class which is used to build other objects polymorphically, based on some form of input. Sometimes used to implement a virtual constructor¤, or as part of a persistent class¤ hierarchy.

Garbage Collection

Any scheme which allows allocated dynamic memory which is no longer required to be "reclaimed" by the dynamic memory manager. The new and delete operators constitute a "manual" garbage collector. Much research is focussed on devising good "automatic" garbage collectors, which watch the program's execution and deduce when specific pieces of dynamically allocated memory are no longer required (which is usually when they are no longer accessible to the program).

Generic

Defined independently from a particular class. Typically used when referring to class or function templates. Also used to refer to pointer variables of type void*, which can be used to store pointers of any type.

Idempotent

An I/O mechanism is idempotent¤ if the output and subsequent input of a value through that system results in no change to the value. In general, the C++ streams are idempotent¤ for integral types (such as bool, char and int), but not for other types (such as float, char* or string).

Implementation

The non-public "internals" of a class, which determine how a class provides the functionality specified by its interface¤.

Implementation Class

A class which exists principally (or solely) to provide the implementation¤ for some other class.

Inorder

An inorder¤ traversal of a tree visits each node in the tree exactly once. At each node, the left sub-tree is visited first (that is, the left child is itself inorder¤ traversed), then the node itself is visited, and finally the right sub-tree is inorder¤ traversed.

Interface

The publicly assessible components of a class, which determine what may be done with a class.

Interface Class

A class which exists principally (or solely) to define a specific interface¤.

Iterators

Objects which act like pointers into a specific type of container class¤. They are specifically designed to simplify the task of sequentially stepping through each element of a container, and are widely used in the STL¤.

Leak

To allocate dynamic memory during a program's execution and then fail to deallocate it before losing access to it. Leaking causes a program to grow in size as it executes, since the dynamic memory manager does not know that it could "reuse" the (now unused) memory which has been allowed to leak¤.

Map class

An class whose instances can be used to store one or more values of a specified type. Each stored value has an associated key (of some specified type) through which it is accessed. The Standard Template Library¤ provides a predefined map class¤.

Mixin

A class representing a specific property or behaviour, which can be added to existing classes by means of multiple inheritance. Mixin¤ classes are typically named with adjectives (for example, SelfLinking, Persistent, Clonable, etc.) denoting the property they confer.

Persistent class

A class whose objects retain their values between executions of a program.

Polymorphism

A property of class hierarchies whereby the result of calling a specific virtual member function of an object depends on the actual (run-time) type of the object, rather than on the (compile-time) type of the pointer or reference through which the call is initiated.

Proxy

A class (or object) which is used in place of some other class (or object), usually to confer some special semantics (such as persistence or access control) that the original class (or object) did not possess.

STL

The usual abbreviation for the C++ Standard Template Library¤.

Specialization

...of a template. A class or function defined by providing an appropriate set of template arguments to a template. For example, class map<Face,Name> is a specialization¤ of the STL¤ template class map.

Standard Template Library

A collection of generic¤ algorithms and data structures provided by all standard-conforming C++ implementations¤.

Swizzled

When an external representation of a name, address, or reference is converted to an internal address (pointer) in main memory, the pointer variable which receives the resulting address is said to have been "swizzled¤".

Utility function

A (usually private) member function of a class which implements some common functionality required by the class public member functions. The use of utility functions¤ improves modularity (and therefore maintainability) by eliminating repeated sequences of code. To avoid loss of run-time performance, utility functions¤ are often declared inline.

Vector

The correct name for a C++ inbuilt array. For example, the declaration:  
 
        int marks[100];  
 
creates a "vector¤ of int of length 100".  
 
Somewhat confusingly, vector¤ is also the name of a basic container class¤ template in the STL¤.

Virtual constructor

A theoretical C++ construct which would create objects according to the actual type required, rather than the apparent type requested. Virtual constructors¤ are usually simulated using a cloneable class¤ or a factory class¤.

Volatile

A C++ type modifier (like const) which indicates to the compiler that objects of the qualified type may change value in ways that it cannot detect (that is, without the execution of explicit program code). More generally, the adjective "volatile¤" is used to describe processes or objects which are subject to unpredictable, frequent, and perhaps dramatic changes (in size, state, value, etc).

Last updated: Fri Feb 18 13:18:50 2000