Nullary constructor

Object-oriented constructors

Java example

publicclass MyInteger{
privateintdata;
// Nullary constructor
publicMyInteger(){
this(0);
}
// Non-nullary constructor
publicMyInteger(intvalue){
this.data=value;
}
intgetData(){
returndata;
}
voidsetData(intvalue){
data=value;
}
}

C++ example

classInteger{
private:
intdata;
public:
// Default constructor with parameters
// Leaving parameters unspecified defaults to the default value
Integer(intvalue=0):
data{value}{}
[[nodiscard]]
intgetData()constnoexcept{
returndata;
}
voidsetData(intvalue)noexcept{
data=value;
}
}

Algebraic data types

Haskell example

-- nullary type constructor with two nullary data constructors
dataBool=False
|True
-- non-nullary type constructor with one non-nullary data constructor
dataPointa=Pointaa
-- non-nullary type constructor with...
dataMaybea=Nothing-- ...nullary data constructor
|Justa-- ...unary data constructor

See also

References