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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".
The form used in C# and the rest of the Common Language Infrastructure is based on that in the classic Visual Basic. delegate void MouseEventHandler ( object sender , MouseEventArgs e ); public class Button : System .
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.
In a software design pattern view, lazy initialization is often used together with a factory method pattern.This combines three ideas: Using a factory method to create instances of a class (factory method pattern)
The observer design pattern is a behavioural pattern listed among the 23 well-known "Gang of Four" design patterns that address recurring design challenges in order to design flexible and reusable object-oriented software, yielding objects that are easier to implement, change, test and reuse. [1]
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]
For function that manipulate strings, modern object-oriented languages, like C# and Java have immutable strings and return a copy (in newly allocated dynamic memory), while others, like C manipulate the original string unless the programmer copies data to a new string.