ZPT: "python: CONTEXTS" gives NameError

[Willem]

In page templates, the built-in variable 'CONTEXTS' is not accessible inside python expressions:

  <div tal:replace="python: CONTEXTS" />
  -> NameError on global name 'CONTEXTS'

while it works fine outside python expressions:

  <div tal:replace="CONTEXTS" />

and the other built-in variables work fine, too:

  <div tal:replace="python: attrs" />

The TALES documentation mentioning CONTEXTS is at:
 <http://www.zope.org/Wikis/DevSite/Projects/ZPT/TALES%20Specification%201.3>

[Evan Simpson (evan-4-am)]

Status: Pending => Resolved

Fixed in HEAD and 2.7 branch.

[LeoRochael (leorochael)]

This bug is once again affects Zope 2.12. It used to work on Zope 2.8 but stopped working at some point and now I have a ton of code affected by it while trying to migrate.

It can be worked around with 'path("CONTEXT")', but it's a pain to convert a bunch of TTW code in formulator instances, and the original version should work. Steps to reproduce are as in the original submission.

It works for path expressions because 'CONTEXTS' is hardcoded there, instead of being added as a variable to the evaluation context.

[Tres Seaver (tseaver)]

- Zope2 no longer bundles a separate TALES implementation. Any fix will
  need to land in zope.tales.

- The docs mention the user of the CONTEXTS special name only when document
  path expressions. I don't even know why you expect to use that name
  elsewhere, but the fact that it happened to work at some point was
  basically an implementation detail. I would plan on fixing your code,
  or else do the work to submit a patch with tests.