[Zope3-dev] Nasty bugs

[Tres Seaver]

On Wed, 20 Mar 2002, Casey Duncan wrote:

> The question then becomes (to me), should we allow primitives to be 
> wrapped at all? Maybe the context wrapper should just pass them through 
> unchanged.
> 
> I can't really see doing security checks on None. I guess I can imagine 
> maybe wanting to know the context of None...Hmmm, 
> WrappedNone.getPhysicalPath() 8^)
> 
> Just thinking out load.

Maybe we need to have custom wrapper types for each of the "special"
primitives, which know how to "be" the underlying thing better?
We would then invoke a "factory method", which would select the correct
wrapper type.

> Jim Fulton wrote:
> > Guido van Rossum wrote:
> > 
> >>I wondered, "why does the z3 root view display a broken image for
> >>Folders?"
> >>
> > 
> > Because icon support hasn't been implemented yet. :) Ditto for the
> > "title" part of the display.
> >  
> > 
> >>There's no single answer.  I found several bugs.  I don't know how to
> >>fix them.
> >>
> >>(1) The page template used,
> >>    Zope3/lib/python/Zope/App/OFS/Folder/main.pt
> >>    contains this text:
> >>
> >>          <img alt="Folder" src="../../ZMI/www/folder_icon.gif"
> >>               tal:condition="info/url"
> >>               tal:attributes="src info/url" />
> >>
> >>    which I believe is a cut-and-paste error, and should really be
> >>
> >>          <img alt="Folder" src="../../ZMI/www/folder_icon.gif"
> >>               tal:condition="info/icon"
> >>               tal:attributes="src info/icon" />
> >>
> > 
> > You are right about the typo, however, the ultimate working code
> > is likely to look much different. I started adding icon support
> > several weeks ago. Among other things, this led to adding resources, 
> > since icons are resources.
> > 
> > For now, we should just take this out of the contents view. I should
> > probably hand off my partial icon work to someone else.
> > 
> > 
> > 
> >>(2) When I fixed that in my copy, I got a traceback, ending in
> >>    "TypeError: len() of unsized object" in method evaluateBoolean()
> >>    in class Context in module TALES, file
> >>    Zope3/lib/python/Zope/PageTemplate/TALES.py (sorry, lost the lineno).
> >>    Casual printing of the evaluation outcome showed that it was doing
> >>    "not not None", which shouldn't trigger this error.
> >>    Printing of its type showed that it's really a wrapper for None,
> >>    and that using it in a Boolean context causes this error.
> >>    Two questions come up:
> >>
> >>    (2a) Why would None need to be wrapped?
> >>
> > 
> > The reason an object would need to be wrapped is if someone wanted 
> > to know how it was obtained. There are a number of reasons that
> > someone might do that:
> > 
> >   - To do security Checks, although this doesn't apply to basic objects
> >     (whatever they are;), like None and numbers, and strings, that
> >     can't have meta-data needed for security checks.
> > 
> >   - Generating URLs. I suppose we don't want to be able to generate 
> >     urls to basic objects.
> > 
> >   - ???
> > 
> > What is actually doing the wrapping here? ZPT path expressions?
> >  
> > 
> >>    (2b) Why can't I use a wrapped None in a Boolean context?
> >>
> > 
> > It's a bug, as I think you've figured out.
> > 
> > ...
> > 
> > 
> >>I could fix the bug in (1), but then the cure would be worse than
> >>the problem (you'd get a traceback from the front page instead of a
> >>broken image icon).
> >>
> >>Please advise.
> >>
> > 
> > 1 should be fixed by not showing the icon (or the title) for now. :)
> > 
> > Jim
> 
> 
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===============================================================
Tres Seaver                                tseaver@zope.com
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