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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".
Bot is a natural type for the "null pointer" value (a pointer which does not point to any object) of languages like Java: in Java, the null type is the universal subtype of reference types. null is the only value of the null type; and it can be cast to any reference type. [2]
In Java, the unit type is called Void and its only value is null. In Go, the unit type is written struct{} and its value is struct{}{}. In PHP, the unit type is called null, which only value is NULL itself. In JavaScript, both Null (its only value is null) and Undefined (its only value is undefined) are built-in unit types.
Nullable types are a feature of some programming languages which allow a value to be set to the special value NULL instead of the usual possible values of the data type.In statically typed languages, a nullable type is an option type, [citation needed] while in dynamically typed languages (where values have types, but variables do not), equivalent behavior is provided by having a single null ...
Unlike a real unit type which is a singleton, the void type lacks a way to represent its value and the language does not provide any way to declare an object or represent a value with type void. In the earliest versions of C, functions with no specific result defaulted to a return type of int and functions with no arguments simply had empty ...
Void safety (also known as null safety) is a guarantee within an object-oriented programming language that no object references will have null or void values. In object-oriented languages, access to objects is achieved through references (or, equivalently, pointers ).
Valhalla is incubating Java language features and enhancements in these areas: [2] [3] Value Classes and Objects: highly-efficient objects without their own identity (reference value). Null-restricted and Nullable types, and Null-restricted Objects: for example, using ? or ! after type declaration to say if null is allowed or not.
The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...