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[#5] Began adding technical details of inheritance to manual

closure/master
Mike Gerwitz 2011-11-09 00:10:52 -05:00
parent 5999223c4e
commit a2926385b5
1 changed files with 37 additions and 7 deletions
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doc/classes.texi
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@ -483,13 +483,43 @@ Define anonymous class @var{C'} as a subtype of @var{base}, described by
object. object.
@end table @end table
Inheritance can be a touchy subject among Object-Oriented developers. It is a @var{C} is a class as defined in @ref{Defining Classes}. @var{base} may be any
powerful feature that is easily abused. @dfn{Inheritance} is the term used to class or object containing enumerable members. @var{dfn} is to be a definition
describe the process of creating a @dfn{child} class that @dfn{extends} object as defined in @ref{Defining Classes}.
(inherits members from) another @dfn{parent} class. The parent class is also
referred to as the @dfn{supertype} and the child is called the @dfn{subtype}. Provided @var{C} or @var{base} to satisfy requirements of @var{C}, class
Let's consider the following example, where we have a dog, a lazy dog, and a dog @var{C'} will be defined as a @dfn{subtype} (child) of @dfn{supertype} (parent)
that walks on two legs: class @var{C}. Provided @var{base} that does @emph{not} satisfy requirements of
@var{C}, @var{C'} will be functionally equivalent to a subtype of anonymous
class @var{B} as defined by @var{B} = Class( @var{base} ).
@subsection Member Inheritance
Let @var{dfn\_n\^c} denote a member of @var{dfn} in regards to class @var{c}
that matches (case-sensitive) name @var{n} and is not private. Let @var{o\_name}
denote an override, represented as boolean value that is true under the
condition that both @var{dfn\_name\^C'} and @var{dfn\_name\^C} are defined
values.
@var{C'} will @dfn{inherit} all public and protected members of supertype
@var{C}. As such, it could be said that @var{dfn\^C'} = @var{dfn\^C} +
@var{dfn}. For any condition @var{o} of any member @var{name}, member
@var{dfn\_name\^C'} will be said to @dfn{override} member @var{dfn\_name\^C},
provided that overriding member @var{name} passes all validation rules
associated with the operation.
For a condition @var{o\_name} where member @var{name} is defined as a method, it
is required that @var{dfn\_name\^C} be declared with the @code{virtual} keyword
and that @var{dfn\_name\^C'} be declared with the @code{override} keyword.
Non-virtual methods cannot be overridden (same as the "final" keyword in
languages like Java).
@subsection Discussion
Inheritance can be a touchy subject among many Object-Oriented developers due to
encapsulation concerns and design considerations over method overrides. The
decision of whether or not inheritance is an appropriate choice over composition
is left to the developer; ease.js provides the facilities for achieving
classical inheritance where it is desired.
@float Figure, f:inheritance-ex @float Figure, f:inheritance-ex
@image{img/inheritance-ex} @image{img/inheritance-ex}