[Zope-dev] Manipulating Meta-Type Global Add list on per-instance basis

[Josh Zeidner]

Hi Tres,

  I Am currently using the scheme that I explained in previous postings in 
an ZClass derived from Object mangager.  However, I am facing one small 
problem.  If the ZClass is defined to have *NO* allowable subobjects, adding 
any meta-types through my code has no effect.  If the ZClass is defined to 
have at least one allowable sub-type, then everything behaves properly.  It 
is my contention that when the first Meta-Type is added through the 
"subobjects" tag, something else is happening that I am not reproducing in 
my code, so...

  1) Do you think this assumption is correct?

  2) What is it that I am missing from my code?

  thanks for all the help... Josh Zeidner



>Josh Zeidner wrote:
> >
> > Hmm... possibly I did not explain my needs :
> >
> >   What I need to do is manipulate the attribute of a "folderish" object 
>(
> > ie. an object that can contain other objects ) that determines what 
>objects
> > are allowed to be contained by my object.  I need to do this at
> > instantiation time , *NOT* definition time.
>
>That is what I was targeting -- I guess my implementation wasn't limpidly
>transparent.
>
> >
> >   I seemed to have accomplished this by manipulating the "meta_types"
> > attribute...  but is this a valid way to attain this behavior?
>
>That is a more straightforward option than I proposed below -- my code 
>_filters_
>the available meta_types based on a tokens/list instance property -- the 
>catch
>is that you have to replace the standard "contents" view in order to get my 
>code
>used (I am not really changing what _could_ be added;  I merely change the 
>list
>presented to the user.)
>
>Munging the meta_types attribute is actually an interesting idea -- 
>"normal"
>Python product objects have the meta_types attribute as a class member;  so 
>in
>fact, you are "hiding" the class member when you assign to the instance
>attribute.  If you ever want to "recover to original," you should be able 
>to
>just "del self.meta_types" hand have it reappear, presto-changeo.
>
>Glad you found a solution.
>
>Tres.
>--
>=========================================================
>Tres Seaver         tseaver@palladion.com    713-523-6582
>Palladion Software  http://www.palladion.com
>
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