[Zope] Sequences and SQL

[Ken Manheimer]

(Was fun to read all the nuances gathered together - nice job michel -
practically the start of a topic guide.  One nuance that i didn't notice
is additional leniency that the non-quoted ("name=", non-expr) dtml
style offers.  Eg, the expression

   <!--#if green_eggs-->

will evaluate to true if the var (or method) green_eggs exists and
evaluates true.  Otherwise it will evaluate to false.  On the other
hand,

   <!--#if "green_eggs"-->

is similar *except* that an exception will be raised if the name
green_eggs is not defined.  The former, non-expr version conveniently
tolerates unbound names.  To tolerate unbound names in an expr you have
to get a lot more verbose - doing something like:

   <!--#if "_.has_key('green_eggs') and green_eggs"-->

While this may seem unnecessary with the non-expr convenience, but
sometimes you need to distinguish definitively between undefined and
false values...)

Ken Manheimer
klm@digicool.com