In programming languages, an abstract type, unlike Concrete class is a type in a nominative type system which cannot be instantiated. (However, it may have concrete subtypes that do have instances.) An abstract type may have no implementation, or an incomplete implementation. It may include abstract methods or abstract properties that are shared by its subtypes.
A type that is not abstract is called a concrete type.
In many object oriented programming languages, abstract types are known as abstract base classes. In some languages, abstract types with no implementation are known as interfaces. Other names for language features that are (or may be) used to implement abstract types include traits, mixins, flavors, or roles.
Read more about Abstract Type: Signifying Abstract Types, Use of Abstract Types
Famous quotes containing the words abstract and/or type:
“Alice grown lazy, mammoth but not fat,
Declines upon her lost and twilight age;
Above in the dozing leaves the grinning cat
Quivers forever with his abstract rage....”
—Allen Tate (1899–1979)
“People forget that it is the eye that makes the horizon, and the rounding mind’s eye which makes this or that man a type or representative of humanity with the name of hero or saint.”
—Ralph Waldo Emerson (1803–1882)