Re: what is abstraction ?

"gk" <srcjnu@gmail.com> writes:


  It means to leave out something.

  For example, in Java, abstracting "3" from the expression

2 * 3

  gives the method

public static int twice( final int x ){ return x * 3; }

  So now, the "2" has been abstracted out of the ... abstraction.
  And the abstraction has been "named" (often "abstraction" is
  a shorthand for the term "named abstraction").

  By naming an abstraction one is lead to the creation of a new concept.

  For example, abstracting even the ?3?

public static int product( final int x, final int x1 ){ return x * x1; }

  yields the concept of multiplication.

  Applying an abstraction to arguments yields or expresses something
  as in ?product( 2, 3 )?.

  The abstraction is a means do dissect a text into chunks
  so that they can be reused. We abstract the parts that restrict
  reuse of something within another context and thus we obtain
  a reusable entity, namely the abstraction.

  An unnamed abstraction would be the lambda-expression

\x.x?3

  where "lambda" was written as "\", but just forget this example,
  if you do not know lambda-calculus or read more about it at
  Google or Wikipedia.


  The bodies of the methods have been abstracted from such a class.