[Zope3-dev] Re: [Zope3-dev] Re: Zope3/src/zope/app/browser/skins/debug/exceptions.py:1.1

[Tres Seaver]

On Wed, 2003-03-12 at 10:57, Steve Alexander wrote:
> 
> > Actually, I'm not worried about *when* the work gets done;  I'm worried
> > about *by whom*.  A component user who wants to customize the display of
> > the traceback will have a much harder time doing so if the component
> > hard-wires its presentation by calling a black-box Python method.
> 
> Are you saying that you'd prefer to design the view for customisation by 
> subclassing, and perhaps have a formatTraceback(tb) method that could be 
> easily overridden?

I want the customization to occur in the template, not in Python.

> > This particular case is tricky, because we *don't* want to keep the
> > actual traceback object around for any length of time.
> 
> It should only be kept around for the duration of the request. Your try: 
> finally: should ensure circular references are broken.

Right.  Note that the 'traceback_lines' don't encode any knowledge of a
particular rendering form:  this view class should work as a base both
for the "show the developer the traceback" page, and for the
hypothetical "generate a mail to the site manager" template.

> I feel like I'm missing your point... :-/  If it looks that way, please 
> put me right.

My main point is that I *don't* want to emit HTML from within a Python
function:  that is what templates are for.  The current implementation
computes a data structure from the traceback, but leaves its
HTML-ification to the template.  This way, when I get lambasted for how
ugly the rendered output is, I can reply, "Customize the template".

> > FWIW, in other work, I do find it a pattern that I will do lots of
> > adapter lookup in the __init__ of the view class, in order to make the
> > adapted content object easily available to the template.
> 
> That could make certain things unnecessarily slow.
> In this case, it would be better to look up the adapters in the method 
> that gets called before a template is rendered. (Which doesn't yet exist.)

I don't imagine that optimizing the "view gets created but not rendered"
case is huge win for the majority of "application"-level views;  I am
glad to be shown wrong, however. :)

Tres.
-- 
===============================================================
Tres Seaver                                tseaver@zope.com
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