[Larceny-users] sqlite3 FFI

[Felix Klock]

On May 30, 2008, at 10:56 PM, Peter Keller wrote:

> Hello,
>
> I have another question, if I may ask:
>
> in my sqlite3 library, I have this:
>
>    (define-c-info (include<> "sqlite3.h")
>      (const SQLITE_INTEGER     int   "SQLITE_INTEGER")
>      (const SQLITE_FLOAT       int   "SQLITE_FLOAT")
>      (const SQLITE_BLOB        int   "SQLITE_BLOB")
>      (const SQLITE_TEXT        int   "SQLITE_TEXT"))
>
> and then later something like this:
>
>    (define sqlite3-column
>      (lambda (stmt colid)
>        (case (sqlite3-column-type stmt colid)
>          ((SQLITE_INTEGER)
>            (sqlite3-column-int stmt colid))
>          ((SQLITE_TEXT)
>            (sqlite3-column-text stmt colid))
>          (else
>            'oops)))) ;; <- obviously this is still test code!
>
> It looks like the SQLITE_INTEGER and SQLITE_TEXT in the sqlite3-column
> function are not available to me (as the code simply doesn't work and
> I get 'oops all the time) while in the library codes. If I replace  
> them
> with the real constants 1 and 3 respectively, or use SQLITE_INTEGER  
> and
> SQLITE_TEXT in a piece of code which imports the sqlite3 library, then
> sqlite3-column behaves properly.
>
> Any ideas?

Are you sure you mean to use Scheme's case special form in the above?

That is, is (sqlite3-column-type stmt colid) going to produce a  
Symbol, or an Integer?  If it produces a Symbol, then your case  
expression might work.  If it produces an Integer, then you will never  
get anything other than 'oops back.

-Felix