[Zope] ZopeTime() and string.split/string.join

[Chris McDonough]

When I call this DTML method (in a container titled "News Items"):

<!--#var standard_html_header-->
<dtml-let tmp_time="title">
  <dtml-var "_.string.join(_.string.split(tmp_time,' '),'_')">
</dtml-let>
<!--#var standard_html_footer-->

I am returned the header, a line that says "News_Items", and the footer.

However, when I call this DTML method:

<!--#var standard_html_header-->
<dtml-let tmp_time="ZopeTime()">
  <dtml-var "_.string.join(_.string.split(tmp_time,' '),'_')">
</dtml-let>
<!--#var standard_html_footer-->

I get the following traceback:

Error Type: TypeError
Error Value: argument 1: expected read-only character buffer, instance found

Traceback (innermost last):
  File /usr/local/Zope-2.0.0/lib/python/ZPublisher/Publish.py, line 214, in
publish_module
  File /usr/local/Zope-2.0.0/lib/python/ZPublisher/Publish.py, line 179, in
publish
  File /usr/local/Zope-2.0.0/lib/python/Zope/__init__.py, line 201, in
zpublisher_exception_hook
    (Object: ElementWithAttributes)
  File /usr/local/Zope-2.0.0/lib/python/ZPublisher/Publish.py, line 165, in
publish
  File /usr/local/Zope-2.0.0/lib/python/ZPublisher/mapply.py, line 160, in
mapply
    (Object: test)
  File /usr/local/Zope-2.0.0/lib/python/ZPublisher/Publish.py, line 102, in
call_object
    (Object: test)
  File /usr/local/Zope-2.0.0/lib/python/OFS/DTMLMethod.py, line 145, in
__call__
    (Object: test)
  File /downloads/Zope-2.0.0-src/lib/python/DocumentTemplate/DT_String.py,
line 502, in __call__
    (Object: test)
  File /downloads/Zope-2.0.0-src/lib/python/DocumentTemplate/DT_Let.py, line
145, in render
    (Object: tmp_time="ZopeTime()")
  File /downloads/Zope-2.0.0-src/lib/python/DocumentTemplate/DT_Util.py,
line 321, in eval
    (Object: _.string.join(_.string.split(tmp_time,' '),'_'))
  File <string>, line 0, in ?
TypeError: (see above)

Why is this?