Nullary constructor

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In computer programming, a nullary constructor is a constructor that takes no arguments. [1] Also known as a 0-argument constructor, no-argument constructor, [2] parameterless constructor or default constructor. [3]

Contents

Object-oriented constructors

In object-oriented programming, a constructor is code that is run when an object is created. Default constructors of objects are usually nullary. [4]

Nullary constructor UML.svg

Java example

publicclassExample{protectedintdata;/* Nullary constructor */publicExample(){this(0);}/* Non-nullary constructor */publicExample(finalintdata){this.data=data;}}

Algebraic data types

In algebraic data types, a constructor is one of many tags that wrap data. If a constructor does not take any data arguments, it is nullary.

Haskell example

-- nullary type constructor with two nullary data constructorsdataBool=False|True-- non-nullary type constructor with one non-nullary data constructordataPointa=Pointaa-- non-nullary type constructor with...dataMaybea=Nothing-- ...nullary data constructor|Justa-- ...unary data constructor

References

  1. ↑ "Default Constructor in Java – Class Constructor Example". freeCodeCamp.org. 2022-01-13. Retrieved 2022-03-23.
  2. ↑ "No-argument Constructor". chortle.ccsu.edu. Retrieved 2022-03-23.
  3. ↑ "Default constructors - cppreference.com". en.cppreference.com. Retrieved 2023-04-12.
  4. ↑ Ottinger, Joseph B.; Linwood, Jeff; Minter, Dave (2022), Ottinger, Joseph B.; Linwood, Jeff; Minter, Dave (eds.), "An Introduction to Hibernate 6" , Beginning Hibernate 6: Java Persistence from Beginner to Pro, Berkeley, CA: Apress, pp. 1–25, doi:10.1007/978-1-4842-7337-1_1, ISBN   978-1-4842-7337-1 , retrieved 2022-03-23


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