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The Collection class in OLE Automation can store items of different data types. Since the data type of these items cannot be known at compile time, the methods to add items to and retrieve items from a collection use variants. If in Visual Basic the For Each construct is used, the iterator variable must be of object type, or a variant.
In object-oriented computer programming, a null object is an object with no referenced value or with defined neutral (null) behavior.The null object design pattern, which describes the uses of such objects and their behavior (or lack thereof), was first published as "Void Value" [1] and later in the Pattern Languages of Program Design book series as "Null Object".
In C++, classes can be forward-declared if you only need to use the pointer-to-that-class type (since all object pointers are the same size, and this is what the compiler cares about). This is especially useful inside class definitions, e.g. if a class contains a member that is a pointer (or a reference) to another class.
The STL includes classes that overload the function call operator (operator ()). Instances of such classes are called functors or function objects . Functors allow the behavior of the associated function to be parameterized (e.g. through arguments passed to the functor's constructor ) and can be used to keep associated per-functor state ...
The Eiffel class ANY contains features for shallow and deep copying and cloning of objects. All Eiffel classes inherit from ANY, so these features are available within all classes, and are applicable both to reference and expanded objects. The copy feature effects a shallow, field-by-field copy from one object to another. In this case no new ...
Many languages have explicit pointers or references. Reference types differ from these in that the entities they refer to are always accessed via references; for example, whereas in C++ it's possible to have either a std:: string and a std:: string *, where the former is a mutable string and the latter is an explicit pointer to a mutable string (unless it's a null pointer), in Java it is only ...
An object's virtual method table will contain the addresses of the object's dynamically bound methods. Method calls are performed by fetching the method's address from the object's virtual method table. The virtual method table is the same for all objects belonging to the same class, and is therefore typically shared between them.
Method overriding, in object-oriented programming, is a language feature that allows a subclass or child class to provide a specific implementation of a method that is already provided by one of its superclasses or parent classes.