----- Original Message ----- From: "Dieter Maurer" <dieter@handshake.de> To: "Li Dongfeng" <mavip1@inet.polyu.edu.hk> Cc: "Zope" <zope@zope.org> 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 use: <dtml-if "_.has_key(local_css) and _['local_css']">

This is equivalent ot "<dtml-if local_css>" with the exception of the caching.

Dieter