[Zope] Temp Folder Magic

[Terry Hancock]

Chris McDonough wrote:
> Even better, maybe just use RAM Cache Manager and give each resized
> image its own URL?
>
> On Sun, 2002-08-11 at 09:31, Chris Withers wrote:
> > Terry Hancock wrote:
> > > Hi all,
> > >
> > > I'm finally revisiting the nasty part of my code
> > > that periodically hoses itself and fails to deliver
> > > resized images. ;-D
> >
> > As a small idea, rather than inheritting from Image and TemporaryFolder, why not
> > subclass Image (but only if you need to change its behaviour ;-) and then store
> > you images in the Temporary Folder in the root of your ZODB?

Naturally I need to change Image's behavior, and indeed
every image does get its own URL (this improves browser
caching as well as any upstream caching).  But for the
system to essentially fail completely without a RAM
cache manager is poor design, IMHO, and puts unnecessary
constraints on the installation, when the product should
really take care of this on its own.

Likewise, using a centralized temporary folder puts
complexity into the ZMI, when it shouldn't be there. I
would then have to create a scheme of URLs for the
temp storage distinct from the original location of
the images. That's going to be very ugly. It's better
to have the caching going on essentially at the source
object.

I considered and rejected both of those designs for
what I consider to be good reasons.  VarImage is a 
utility class and gets used for several different
things in several places. To dump the complexity up
a layer to the calling code just doesn't make sense.

I *had* considered making the temp folder *contained*
by the Image and not a superclass of it.  But I'd still
like to understand how and why a Temp folder comes into
being. The source is not immediately transparent on
this point.  Why did it need to be different from other
Zope objects? Why is there no such thing as a "Temporary
Folder" class in Zope?  I thought we liked object oriented
programming. ;-D  Now all of a sudden we abandon it.
There must be a reason for that.

It seems to me that it's impossible to subclass Temporary
Folder, because there's no such class.  I'd like to
think that's wrong.

Thanks, 
Terry

-- 
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Terry Hancock
hancock@anansispaceworks.com       
Anansi Spaceworks                 
http://www.anansispaceworks.com 
P.O. Box 60583                     
Pasadena, CA 91116-6583
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