[Zope] Nice to have feature.

[Edward Ing]

I place the following feature request into the bug/feature/patch collector,
but the submission failed.
Anyways, I would like to have feed back from users here.

It would be nice if path expressions could be the result of an expansion
evaluation.
If you could have a tag expression as follows:
<span tal:replace="structure ${request/middle_section_template}">middle
section to be replaced</span>
where the value of the path request/middle_section_template is the path (and
hence another level of indirection) this feature would make page layout more
elegent.

Right now I can acheive the same "late template binding" via python script.
But the above feature would be nicer and more elegant.
For instance if the following code is on my main application template page
and I had two middle section templates, one for a corporate application form
and one for an individual application form,  one of which should be merged
depending on a runtime variable of whether the user is applying for his
company or for himself:
I would like to be able to set,
    REQUEST.middle_section_template="container/CorporateFormPageTemplate",
or set,
REQUEST.middle_section_template="container/IndividualFormPageTemplate",
depending on whether the user is a corporation or and individual.
And then have the evaluation of the expression
${request/middle_section_templage} determine the replacement path.
This seems like something easy to do, because in the page template string
expression a similar evaluation is taking place.