[Zope-dev] Zope2 debug-mode vs ZCML dev-mode, ZCML conditionals

[Thomas Lotze]

We recently ran into an issue with debug/development mode when making
z3c.hashedresource work with Zope2: The package implements different
behaviour depending on whether the dev-mode feature is enabled in the ZCML
of a Zope3 application, and we sort of expected this feature to be
automatically enabled or disabled in a Zope2 application using Five when
Zope2 debug-mode is switched on or off, resp. As this doesn't seem to be
the case, we were wondering a few things:

- Is Zope2 debug mode semantically equivalent to ZCML dev-mode, i.e.
  should the two be linked to each other in the first place?

- If so, is it a bug that ZCML dev-mode isn't controlled by Zope2 debug
  mode in a Five application? Or is it and we're just missing something?

- If the the two should be connected but aren't, what's the best way to
  fix things? Should this be fixed in Five? Otherwise, how to achieve
  switching on the ZCML dev-mode feature the right way?

Independently of these questions, wouldn't it make sense for ZCML to have,
in addition to "feature" and "installed", a conditional verb "expression"
that allows referencing a Python expression defined in a module whose
boolean value to use for deciding the condition?

-- 
Thomas