[Zope] Testing multiple values for existance - still

[Oliver Sturm]

On 25.09.2001 10:24:48 -0400 Phil Harris <phil.harris@zope.co.uk> wrote:

> You are missing the distinction between:
> 
> <dtml-if foo>
> 
> and 
> 
> <dtml-if "foo and bar">
> 
> You're also missing some of the maddening Zope 'Magic'.
> 
> The first statement tests first for existence, and only then for value.
> The second assumes existence and only tests for value.

I got that at last :-). But WHY? I reckon it may be as simple as that the
"'s render the whole thing a Python expression instead of something that can
be handled directly by Zope. Is that so? If yes, I'd consider that a large
drawback and inconsistency... and does Python syntax for the test have to be
so complicated?

> In your case I think you were testing for the esitence of a method, not
> of a variable, am I right?  If foo doesn't exist then the first test
> returns false because foo is not in the currrent namespace, the second
> though drops into Python rules and has none of the Zope 'magic' applied.

That's right (I think). Although I have never actually found many
differences between methods and variables when it comes to their use in
expressions (up to now, that is). I was considering it one of the strengths
of Zope to work with objects of different types without apparent
distinctions.

> I hope this goes someway to explain what you asked, of course if you'd
> said explicitly that you were testing for the existence of methods in
> the current folder, then this could be made a bit simpler.

I didn't assume people would think I was doing so very complicated things. I
usually structure Zope sites in a way that allows me to work with objects in
the current context (folder?) 99% of the time, praise acquisition.

Now, are there even simpler ways to test for alternate existence of more
than  one method in the current folder?

Thanks for your help!

Oliver

-- 
Oliver Sturm / <sturm@oliver-sturm.de>