[Zope] object icons

[Martijn Pieters]

From: Loren Stafford [mailto:lstaffor@dynalogic.com]
> 
> As usual, I blabbered on before I knew what I was talking about.
> 
> I played some more with this (because I have the same problem 
> in my product)
> and found that the "Product Icons" section at
> http://www.zope.org/Members/Zen/howto/ProductAPITutorial does 
> indeed work as
> documented:
> 
> 
> 
>                       Here's our poll's misc_ definition:
> 
>                              misc_={
>                                  'poll': 
> ImageFile('poll.gif',globals()),
>                              }
> 
> 
>                       It only defines one thing--the poll's 
> icon. For your
> Product's icons you should use 'ImageFile's.
> 
>                       Objects defined in a Product's misc_ 
> mapping are made
> available through the web at /misc_//.
> 
>                       To allow Zope to find this icon you 
> need to specify
> its URL in your Product's class. So here's how we indicate our poll's
>                       icon:
> 
>                              class Poll:
>                                  ...
>                                  icon='misc_/Poll/poll'
>                                  ...
> 
> You just have to realize that icon="misc_/<ProductID>/<misc_key>".

The Misc object is a special object for storing things like the actual
data for product icons. Using context.registerClass automates the
process of storing an icon in the misc_ structure (containing Misc
objects), and having your class.icon URL attribute pointing at the URL
for that icon.

Doing so makes it easier for your product to have an icon, and you don't
have to worry about setting the icon attribute correctly. Just leave out
the icon attribute of you class, and pass in the (relative) path to your
icon. See, for example, lib/python/Products/ZCatalog/__init__.py.

You will only want to mess with the icon attribute when you want to
dynamically change the icon of your class. You'd have to store the icons
manually in the misc_ structure, like Loren described, and manually set
your icon attribute to URLs to those icons.

-- 
Martijn Pieters, Software Engineer 
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