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Added temporary instance section to manual

closure/master
Mike Gerwitz 2011-03-15 21:31:51 -04:00
parent eab74cb9de
commit 3f7721d0ab
1 changed files with 43 additions and 3 deletions
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doc/classes.texi
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@ -134,9 +134,9 @@ capital, for class names (and nothing else).
@menu @menu
* Anonymous vs. Named Classes:: * Anonymous vs. Named Classes::
* Temporary Classes:: Throwaway classes that only need to be used once * Temporary Classes:: Throwaway classes that only need to be used once
* Temporary Instances:: Throwaway instances that only need to be used once
@end menu @end menu
@node Anonymous vs. Named Classes @node Anonymous vs. Named Classes
@subsection Anonymous vs. Named Classes @subsection Anonymous vs. Named Classes
We state that @ref{f:class-easejs,} declared an @dfn{anyonmous class} because We state that @ref{f:class-easejs,} declared an @dfn{anyonmous class} because
@ -201,7 +201,6 @@ functionally no difference between named and anonymous classes.}
Much better! We now have a useful error message and immediately know which class Much better! We now have a useful error message and immediately know which class
is causing the issue. is causing the issue.
@node Temporary Classes @node Temporary Classes
@subsection Temporary Classes @subsection Temporary Classes
In @ref{f:class-easejs,}, we saw that the @code{new} keyword was unnecessary In @ref{f:class-easejs,}, we saw that the @code{new} keyword was unnecessary
@ -244,3 +243,44 @@ variable rather than an actual class definition. If you follow the CamelCase
convention for class names, then simply do not capitalize the first letter of convention for class names, then simply do not capitalize the first letter of
the destination variable for the instance. the destination variable for the instance.
@node Temporary Instances
@subsection Temporary Instances
Similar to @ref{Temporary Classes,}, you may wish to use an @emph{instance}
temporarily to invoke a method or chain of methods. @dfn{Temporary instances}
are instances that are instantiated in order to invoke a method or chain of
methods, then are immediately discarded.
@float Figure, f:inst-tmp
@verbatim
// retrieve the name from an instance of Foo
var name = Foo().getName();
// method chaining
var car = VehicleFactory().createBody().addWheel( 4 ).addDoor( 2 ).build();
// temporary class with callback
HttpRequest( host, port ).get( path, function( data )
{
console.log( data );
} );
// Conventionally (without ease.js), you'd accomplish the above using the
// 'new' keyword. You may still do this with ease.js, though it is less
// clean looking.
( new Foo() ).someMethod();
@end verbatim
@caption{Declaring a temporary (throwaway) class}
@end float
Rather than storing the class instance, we are using it simply to invoke
methods. The results of those methods are stored in the variable rather than the
class instance. The instance is immediately discarded, since it is no longer
able to be referenced, and is as such a temporary instance.
In order for method chaining to work, each method must return itself.
This pattern is useful for when a class requires instantiation in order to
invoke a method. Classes that intend to be frequently used in this manner should
declare static methods so that they may be accessed without the overhead of
creating a new class instance.