[Zope] Test whether ZClass lines type property is empty

[complaw@hal-pc.org]

I've had this problem too.  

Instead of checking for length, I check to see if the first 
item on the list is <> ''.  If there is nothing in the first
item, then I assume that it is an empty list.  For the most
part, the assumption is valid.

for x in my_list:
  if x <> '':
    # do something...


Hope that helps,

Ron

> ZClass "lines" type property is a "list" in Python.
> 
> If there are no values, it should render IMHO as an empty list in
> Python: []
> 
> But it renders as a list containing single item. Something like: [""]
> 
> Consequently, len(variable) is 1, whether there is one line or no lines.
> 
> I cannot use <dtml-if "_.len(variable)>0"> to see if there are values.
> 
> How can I discover if the list is empty without computationally
> expensive constructs?
> 
> --
> Milos Prudek
> 
> 
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