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Re: [Chicken-users] New immediate values (was: DBI)
From: |
Tobia Conforto |
Subject: |
Re: [Chicken-users] New immediate values (was: DBI) |
Date: |
Fri, 29 Feb 2008 20:57:47 +0100 |
So, to recap:
'(), 0, "", #f, 'null, (gensym)
Very bad for representing SQL NULL, because some DBs or DB operations
could theoretically support lists, numbers (doh), strings (doh),
booleans, and symbols, and in those cases we wouldn't want the null
value to clash with valid values.
For example I'd quite like to see a Postgres extension (or just the
Chicken interface) supporting symbols in an efficient manner, with a
symbol table and all. As it can't be ruled out, having symbol? return
#t for sql NULL is a very bad idea.
(void)
Bad. You would need to test for it by (eq? x (void)), which is
terrible, and is a non-value inappropriate for representing an actual
return value, as already expressed in this thread.
(define-record-type sql-null (sql-null) sql-null?)
Not too bad. Any piece of code could create null values with (sql-
null), even in different compilation units. People would just have to
remember to use (sql-null? x) instead of eq?. The API could state
that eq? on two sql-null values is undefined.
A new immediate value
IMHO the best option, and it could be useful for other APIs too, but
if Felix says no he's probably right.
Tobia
- Re: [Chicken-users] DBI, (continued)
- Re: [Chicken-users] DBI, felix winkelmann, 2008/02/28
- Re: [Chicken-users] DBI, Graham Fawcett, 2008/02/28
- [Chicken-users] New immediate values (was: DBI), Tobia Conforto, 2008/02/28
- Re: [Chicken-users] New immediate values (was: DBI), Graham Fawcett, 2008/02/28
- Re: [Chicken-users] New immediate values (was: DBI), John Cowan, 2008/02/28
- Re: [Chicken-users] New immediate values (was: DBI), Mario Domenech Goulart, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), felix winkelmann, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Tobia Conforto, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), felix winkelmann, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Graham Fawcett, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI),
Tobia Conforto <=
- Re: [Chicken-users] New immediate values (was: DBI), Graham Fawcett, 2008/02/29
- Re: [Chicken-users] New immediate values, Ozzi Lee, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), John Cowan, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), felix winkelmann, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Alaric Snell-Pym, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), John Cowan, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Alaric Snell-Pym, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), John Cowan, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Alaric Snell-Pym, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), John Cowan, 2008/02/29