What are OOP's Jargons and Complexities?

[Xah Lee]

The Rise of “Constructors” and “Accessors”

A instantiation, is when a variable is assigned a super-subroutine
(class). A variable assigned such a super-subroutine is now called a
instance of a class or a object.

In OOP practice, certain inner-subroutines (methods) have developed
into specialized purposes. A inner-subroutine that is always called
when the super-subroutine is assigned to a variable (instantiation), is
called a constructor or initializer. These specialized
inner-subroutines are sometimes given a special status in the language.
For example in Java the language, constructors are different from
methods.

In OOP, it has developed into a practice that in general the data
inside super-subroutines are supposed to be changed only by the
super-subroutine's inner-subroutines, as opposed to by reference thru
the super-subroutine. (In OOP parlance: class's variables are supposed
to be accessed/changed only by the class's methods.) Though this
practice is not universal or absolute. Inner-subroutines that change or
return the value of variables are called accessors. For example, in
Java, a string class's method length() is a accessor.

Because constructors are usually treated as a special method at the
language level, its concept and linguistic issues is a OOP machinery
complexity, while the Accessor concept is a OOP engineering complexity.

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to be continued tomorrow.

This is part of an installment of the article
“What are OOP's Jargons and Complexities”
by Xah Lee, 20050128. The full text is at
 http://xahlee.org/Periodic_dosage_dir/t2/oop.html

© Copyright 2005 by Xah Lee. Verbatim duplication of the complete
article for non-profit purposes is granted.

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 Xah
 xah at xahlee.org
∑ http://xahlee.org/