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From "Rice Yeh" <rice...@gmail.com>
Subject Re: Circular deps in servlet connections (was Re: Servlet Services + Shielding)
Date Wed, 04 Apr 2007 06:14:57 GMT
On 4/4/07, Grzegorz Kossakowski <gkossakowski@apache.org> wrote:
>
> Alexander Klimetschek napisaƂ(a):
> > Grzegorz Kossakowski schrieb:
> >
> > We do need the circular dependency: the basic principle is a super
> > block that runs cforms that are mainly defined in a child block - the
> > model lies in the child block and it contains a selection-list whose
> > source is block:child:/some/matcher - hence the circle, because the
> > selection-list will be resolved inside the super block.
>
> Let me tell you how i *imagine* servlet-service-fw should deal super
> calls and tell me how it's different from current situation. This should
> help us both.
> Let's have two blocks, one named "base" and one "extending", base is
> super block for extending. I've imagined (before using super calls) that
> it would work that way:
> extending block is requested for "someResource" and suppose it has not
> any matching pattern for it, then super (base in our case) block is
> automatically asked for the same. You don't have to provide any generic
> matcher that redirects processing to super block.
> Now someResource is catched by base block but it asks for
> "internalResource" by calling "servlet:internalResource". Given that
> base block is called as super of extending, first extending block is
> asked for this resource (because it may override it) and if it does not
> provide one, it's taken from base block.
>
> In short: I mean that super should work as fallback mechanism. I guess


The idea directly applies to OO's inheritance definition. However,
it might not be easy to implement because it is hard to define "the
looked-up resource does not exist in the extending servlet." Take flowscript
as example, it is usually a javascript error when calling a method of a
non-existent javascript object which exists in the super servlet but matched
in the extending servlet's sitemap.


it does not work that way now. However, this would eliminate need for
> circular dependencies and give cleaner design.
>
> What do you think?
>
> --
> Grzegorz Kossakowski
>
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