[Zope] Strange CSS inclusion BUG
Wed, 20 Sep 2000 10:43:49 +0800
----- Original Message -----
From: "Dieter Maurer" <email@example.com>
To: "Li Dongfeng" <firstname.lastname@example.org>
Cc: "Zope" <email@example.com>
Sent: Wednesday, September 20, 2000 3:25 AM
Subject: Re: [Zope] Strange CSS inclusion BUG
> Li Dongfeng writes:
> > To use CSS file, I put the following line in the head of HTML files:
> > <dtml-if local_css>
> > <link href="<dtml-var "local_css.absolute_url()">"
> > rel="stylesheet" type="text/css">
> > </dtml-if>
> > Where "local_css" is a DTML document containing CSS style sheet.
> > But the DTML generates the following error message:
> > Error Type: AttributeError
> > Error Value: 'string' object has no attribute 'absolute_url'
> > If I strip the <dtml-if protection, the code works OK.
> > Why is the DTML document local_css changed into a string
> > after <dtml-if>?
> That is a dtml-if caveat!
> The dtml-if documentation says that dtml-if caches its
> variable value to save time, in case the variable is
> in fact a function that takes long to call.
> What happens in your case:
> <dtml-if local_css> looks up "local_css" and because
> it is callable, it gets called (i.e. rendered).
> The result is a string. This string is bound to
> "local_css" inside the <dtml-if>...</dtml-if>.
> Therefore, "local_css.absolute_url" results in
> the error you observed.
> You can replace <dtml-if local_css> by
> <dtml-if "_.has_key(local_css)">.
This really works! Even when the request is from a folder
below where local_css resides. This success sugests that
"_.has_key()" also use aquisition to search for objects.
> This will not be equivalent to "<dtml-if local_css>" but
> good enough for your purpose.
> If you want to emulate it more faithfull, you could
> <dtml-if "_.has_key(local_css) and _['local_css']">
> This is equivalent ot "<dtml-if local_css>" with the
> exception of the caching.