[Zope] Re: Testing types in TAL
tseaver at zope.com
Fri Nov 12 14:12:35 EST 2004
Alec Mitchell wrote:
> So I've run into a minor TAL problem recently. I'm trying to test to see if
> an object is a List or a Tuple (or more generally a sequence that isn't a
> string), but can't figure out a way. I've tried the following:
> python:isinstance(obj, list)
> doesn't work (it doesn't recoginze 'list' as a 'class, type or tuple of
> classes and types'), strangely:
> python:isinstance(obj, str)
> works ('str' is ok, but not 'list' or 'tuple'?). Also:
> works despite the fact that 'list' is not recognized as a class!
> python:type(obj) is type()
> fails because type() is not recognized in TAL.
> python:hasattr(obj, '__iter__')
> fails also, though I'm not sure why (probably TAL doesn't bother with
> variables starting with '_').
> And it's impossible to pull 'ListType' etc. in using modules['types'], because
> of the lack of security assertions on the 'types' module.
> There must be a way to do a simple type check for a tuple without a python
> script, no? Right now I'm using:
> tal:define="dictish nocall:obj/keys|nothing;
> listish python:not dictish and len(obj) and (len(obj) != 1)"
> Which is far too kludgy, brittle, and plain incorrect for my liking.
'same_type' is what you want:
Tres Seaver tseaver at zope.com
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