Use of Abstract Types
Abstract types are an important feature in statically typed OO languages. Many dynamically typed languages have no equivalent feature (although the use of duck typing makes abstract types unnecessary); however traits are found in some modern dynamically-typed languages.
Some authors argue that classes should be leaf classes (have no subtypes), or else be abstract.
Abstract types are useful in that they can be used to define and enforce a protocol; a set of operations which all objects that implement the protocol must support.
Read more about this topic: Abstract Type
Famous quotes containing the words abstract and/or types:
“But it thought no bed too narrow—it stood with lips askew
And shook its great head sadly like the abstract Jew.”
—Robert Penn Warren (1905–1989)
“Our children evaluate themselves based on the opinions we have of them. When we use harsh words, biting comments, and a sarcastic tone of voice, we plant the seeds of self-doubt in their developing minds.... Children who receive a steady diet of these types of messages end up feeling powerless, inadequate, and unimportant. They start to believe that they are bad, and that they can never do enough.”
—Stephanie Martson (20th century)