[stringtemplate-interest] null vs missing vs empty vs nonexistent

[Harry Karadimas]

Reminds me of the debates about SQL Null

http://en.wikipedia.org/wiki/Null_(SQL)

One other question is :

What must the user know about handling of null values to use st ?

If st becomes too complex, this will also hinder its adoption, so
maybe let's not put too many operators/values/cases/options/etc.

For me mainly three cases are relevant :

* there is no attribute named "foo"
* there is an attribute named "foo", and its value is : null
* there is an attribute named "foo", and its value is a string,
  which is : "...(whatever, including the empty string)"

Maybe a fourth case to test if the value is the empty string
could be relevant, and this would autmatically lead to a fifth
case where the trimmed value (removing all spaces, tabs, 
form feeds, vertical form feeds, ...) is the empty string.

My 1,3412 cents (we use euros in France) ...


                                                  Harry Karadimas

______________________________________________________________________
Dr Harry Karadimas,  Medecin Ingenieur
resp. Recherche et Developpement, Applications medicales
Departement d'Information Hospitalier (DIH)
C.H.U. Albert Chenevier - Henri Mondor 
51, av. du Marechal de Lattre de Tassigny               94010  CRETEIL