Swapped 'Overriding Methods' and 'Type Checks and Polymorphism' due to referring content
Mike Gerwitz
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110
doc/classes.texi
110
doc/classes.texi
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@ -392,9 +392,9 @@ conciseness.
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@menu
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* Understanding Member Inheritance:: How to work with inherited members
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* Overriding Methods:: Overriding inherited methods
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* Type Checks and Polymorphism:: Substituting similar classes for
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one-another
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* Overriding Methods:: Overriding inherited methods
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@end menu
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@node Understanding Member Inheritance
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@ -459,6 +459,60 @@ inherited from @var{Dog}. If we actually run the example, you will notice that
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the dog does indeed bark, showing that we are able to call our parent's method
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even though we did not define it ourselves.
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@node Overriding Methods
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@subsection Overriding Methods
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When a method is inherited, you have the option of either keeping the parent's
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implementation or overriding it to provide your own. When you override a method,
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you replace whatever functionality was defined by the parent. Using this concept
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is how we made our lazy dog lazy and our two-legged dog walk on two legs in
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@ref{f:inheritance}.
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After overriding a method, you may still want to invoke the parent's method.
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This allows you to augment the functionality rather than replacing it entirely.
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ease.js provides a magic @code{__super()} method to do this. This method is
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defined only for overriding methods and calls the parent method that was
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overridden.
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In order to demonstrate this, let's add an additional subtype to our hierarchy:
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@var{AngryDog}. @var{AngryDog} will be a subtype of @var{LazyDog}. Not only is
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this dog lazy, but he's rather moody.
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@float Figure, f:super-method
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@verbatim
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var AngryDog = Class( 'AngryDog' ).extend( LazyDog,
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{
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'public poke': function()
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{
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// augment the parent method
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console.log( 'Grrrrrr...' );
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// call the overridden method
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this.__super();
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}
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} );
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// poke a new AngryDog instance
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AngryDog().poke();
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// Output:
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// Grrrrrr...
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// Woof!
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@end verbatim
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@caption{Using @code{__super()} method}
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@end float
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If you remember from @ref{f:using-inherited-members}, we added a @code{poke()}
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method to @var{LazyDog}. In @ref{f:super-method} above, we are overriding this
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method so that @var{AngryDog} growls when you poke him. However, we still want
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to invoke @var{LazyDog}'s default behavior when he's poked, so we also call the
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@code{__super()} method. This will also make @var{AngryDog} bark like
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@var{LazyDog}.
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It is important to note that @code{__super()} must be invoked like any other
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method. That is, if the overridden method requires arguments, you must pass them
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to @code{__super()}. This allows you to modify the argument list before it is
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sent to the overridden method.
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@node Type Checks and Polymorphism
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@subsection Type Checks and Polymorphism
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The fact that the API of the parent is inherited is a very important detail. If
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@ -566,60 +620,6 @@ Currently, it is necessary to perform this type check yourself. In future
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versions, ease.js will allow for argument type hinting/strict typing, which will
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automate this check for you.
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@node Overriding Methods
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@subsection Overriding Methods
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When a method is inherited, you have the option of either keeping the parent's
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implementation or overriding it to provide your own. When you override a method,
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you replace whatever functionality was defined by the parent. Using this concept
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is how we made our lazy dog lazy and our two-legged dog walk on two legs in
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@ref{f:inheritance}.
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After overriding a method, you may still want to invoke the parent's method.
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This allows you to augment the functionality rather than replacing it entirely.
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ease.js provides a magic @code{__super()} method to do this. This method is
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defined only for overriding methods and calls the parent method that was
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overridden.
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In order to demonstrate this, let's add an additional subtype to our hierarchy:
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@var{AngryDog}. @var{AngryDog} will be a subtype of @var{LazyDog}. Not only is
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this dog lazy, but he's rather moody.
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@float Figure, f:super-method
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@verbatim
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var AngryDog = Class( 'AngryDog' ).extend( LazyDog,
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{
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'public poke': function()
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{
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// augment the parent method
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console.log( 'Grrrrrr...' );
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// call the overridden method
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this.__super();
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}
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} );
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// poke a new AngryDog instance
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AngryDog().poke();
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// Output:
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// Grrrrrr...
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// Woof!
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@end verbatim
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@caption{Using @code{__super()} method}
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@end float
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If you remember from @ref{f:using-inherited-members}, we added a @code{poke()}
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method to @var{LazyDog}. In @ref{f:super-method} above, we are overriding this
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method so that @var{AngryDog} growls when you poke him. However, we still want
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to invoke @var{LazyDog}'s default behavior when he's poked, so we also call the
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@code{__super()} method. This will also make @var{AngryDog} bark like
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@var{LazyDog}.
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It is important to note that @code{__super()} must be invoked like any other
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method. That is, if the overridden method requires arguments, you must pass them
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to @code{__super()}. This allows you to modify the argument list before it is
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sent to the overridden method.
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@node Member Visibility
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@section Member Visibility
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