Clean way to do string.join

Hi all:

            I like to use a lot string functions since formulating an
expression can be a pain.   I tried to use string.join to make a simple
AND clause, "X AND Y AND Z", any of them can be empty, i.e., if X is
empty, it becomes "Y AND Z".   However I noticed string.join is not that
smart, it does not treat empty string or null string differently, and
output " AND Y AND Z".

 

            I hate to do an elaborate if else since I need to do
multiple branches for different combinations.  Any efficient way to
address string.join's short coming?  Shouldn't it no do a join if string
element is empty?

 

            

 

 

 



[Non-text portions of this message have been removed]