Re: Global concept

hi,

perhaps i'm a little daft, but i dont get it... if - as you said below -
you're creating it as a singleton, why do you even need framework support
for it, instead of just writing MyFoo.getInstance()?

i'm aware, there are some classloading issues with a singleton (although
this has not come up as a problem for me in recent containers), so i keep
my stuff in the ServletContext as it's supposed to be - but since that
would be inconvenient to access, i usually wrap my stuff around with some
code that sets it up as a ThreadLocal (that is statically accessible)...
so it becomes very convenient to access (anywhere with no casting), since
i can still say MyFoo.getInstance(), and have the flexibility as to where
it's really coming from (eg. it doesnt strictly need to be "global")...
also, i have some concerns about having only one global... you would
probably need a Map of them... and you still need to the casting
everywhere you need it...

so, i wouldn't bother to add this to the Tapestry framework itself, it
already supports what you need, here's an example:
http://flock.sourceforge.net/xref/net/sf/flock/webapp/FlockTapestryEngine.html
http://flock.sourceforge.net/xref/net/sf/flock/webapp/FlockContext.html

... and you set it up in the application servlet init() for example, or
lazy-init, or whatever works for you.

best regards,
    viktor

On Mon, 30 Dec 2002 06:37:36 -0500, "Howard M. Lewis Ship"
<[email protected]> said:
> A very good idea, I think.
> 
> ----- Original Message -----
> From: "Malcolm Edgar" <[email protected]>
> To: <tapestry-contrib-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
> Sent: Monday, December 30, 2002 5:59 AM
> Subject: [Tapestry-contrib] Global concept
> 
> 
> > After Howards email about Visit object names including Global, I started
> > thinking it would be really good to have a shared global object in
> Tapestry.
> >
> > I want to kick off a discussion before putting in a Feature Request.
> >
> > Regards Malcolm
> >
> > Global
> > ======
> >
> > Aim
> > ---
> > Provide a shared global object that can be used for globally accessed data
> > or utility methods. Currently it is recommended that the SimpleEngine be
> > subclassed to provide a point to hang shared data off, or access global
> data
> > via the ServletContext accessed from the IRequestCycle.
> >
> > Conceptually it simpler to have a global object available throughout the
> > framework.
> >
> > Design
> > ------
> > A global bean object modelled on the access style of the Visit object.
> >
> > The global object would have an accessor method added to IPage interface:
> >
> > public Object getGlobal();
> >
> > This object would be instantiated via a no args condtructor, with the
> class
> > name specified in the Application.specification as is done with the visit
> > object. This object should follow a singleton style design pattern, so
> their
> > is only ever one instance available.
> >
> > This object should be stored in the ServletContext under the key
> > 'net.sf.tapestry.global' so that it can potentially be shared with other
> > Servlet components.
> >
> > Scope
> > -----
> > Global object: shared application data
> > Visit object: user specific data
> > Persistent page properties: user page specific data
> >
> > Example Usage
> > -------------
> > Application properties
> > Application constants
> > Cached data
> > Connection DataSources
> >
> >
> >
-- 
  
  [email protected]

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