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C# is a language in which the null object pattern can be properly implemented. This example shows animal objects that display sounds and a NullAnimal instance used in place of the C# null keyword. The null object provides consistent behaviour and prevents a runtime null reference exception that would occur if the C# null keyword were used instead.
In computer programming, lazy initialization is the tactic of delaying the creation of an object, the calculation of a value, or some other expensive process until the first time it is needed.
The original form of the pattern, appearing in Pattern Languages of Program Design 3, [2] has data races, depending on the memory model in use, and it is hard to get right. Some consider it to be an anti-pattern. [3] There are valid forms of the pattern, including the use of the volatile keyword in Java and explicit memory barriers in C++. [4]
An example of the application of marker interfaces from the Java programming language is the Serializable interface: package java.io ; public interface Serializable { } A class implements this interface to indicate that its non- transient data members can be written to an ObjectOutputStream .
The object pool pattern is a software creational design pattern that uses a set of initialized objects kept ready to use – a "pool" – rather than allocating and destroying them on demand. A client of the pool will request an object from the pool and perform operations on the returned object.
The examples are still bad, though. The C example misses the concept entirely (the pattern requires the concept of objects, so I don't know that this pattern can be implemented in C) and while an empty C# array may exhibit similar behavior to a null object, it certainly isn't a good example of the practical use of the pattern.
The builder pattern is a design pattern that provides a flexible solution to various object creation problems in object-oriented programming.The builder pattern separates the construction of a complex object from its representation.
The pattern consists of six elements: [3] A proxy, which provides an interface towards clients with publicly accessible methods. An interface which defines the method request on an active object. A list of pending requests from clients. A scheduler, which decides which request to execute next. The implementation of the active object method.