Re: [PW-dev] Static methods - was Widget factory

[Issac G. <ne...@wr...>]

> At 05:08 PM 6/11/2001 -0500, you wrote:
> >"Jay Lawrence" <Ja...@La...> wrote:
> >>James and Stephen,
> >>
> >>Could you please expand on what you mean by static methods?
> >
> >These would be methods that are not tied to an instance -- the `new'
method
> >(basically, any constructor) is an example of a usually static method.
Any
> >method that requires an instance of an object class is not a static
method.
> >
> >Perl blurs the line between static and non-static methods.  C++ is very
> >explicit and requires the `static' keyword before the function
declaration.
> >
> >The static methods do not have an object to get any information from, so
any
> >configuration information they get would have to either come from the
> function
> >arguments or from globals.
> >--
> >James Smith <JG...@TA...>, 979-862-3725
> >Texas A&M CIS Operating Systems Group, Unix
> >
>
> James is correct on all points.
> For example
>
>    $wc = Widget->controller();
>
> is a "static" method on the Widget package.  No instance of a "Widget"
class
> was required in order to call the controller() method.  Any routine called
> from the package name (i.e. Package::Name->method_name()) is a static
method.
> (The terminology indeed comes from C++ and Java.)
>
> A "normal" method call (dynamic?) is called on an instance of a class.
i.e.
>
>    $query = CGI->new();       # this is a static method call, called from
> package
>    print $query->param("x");  # this is a normal (dynamic) method call,
> called from object
>
> The "Factory" pattern is a standard way of constructing objects without
> knowing
> what type of objects they actually are.  In order to instantiate an
object,
> you
> normally need to know the class of the object.  With a factory, you can
let
> the
> factory decide.  In this way,
>
>    $wc = Widget->controller();
>
> is letting the static method, "controller()", in the Widget package decide
> which
> class it should instantiate when returning a Controller.
> Similarly, with
>
>    $date_widget = $wc->widget("date");
>
> we are letting the controller decide (based on config and runtime
information)
> what actual class to instantiate.
>
> Thus, both the Widget package and Widget::Controller objects are acting as
> factories
> in the PWL.
>
> Stephen

Wait a second... I was under the impression that the Widget::COntroller
object simply got "bound" to a top level Widget object somewhere...  That
you couldn't actually go about creating the actual Widgets until you had an
instantiated Controller....  Am I barking up wrong trees here???

  Issac

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