FreeTDS Development Group

[Joe Losco <joe AT sqpuv.com>]

James K. Lowden wrote:
> My first instinct was to wonder if in fact you're linking to FreeTDS and
> not one of the vendor libraries, or perhaps to a version prior to 0.82.  I
> assume none of those is the case.  
>
> My second guess is to wonder if Objective C is looking at the header file
> (or something like that), interpreting each nonzero return code as "true",
> and returning only 0 or 1.  Is there glue code that allows Objective C to
> call a C library?  Is there some preprocessing that gets done to make C
> functions available to it?  
>
> If so, the solution might be to define the function as returning DBINT
> instead of DBBOOL.  Or something like that.  
>
>
>   
I have thought about this a little more and have thought of something I 
had "fixed" for Obj-C that I thought was irrelevant, however now with 
the information about the results that dbwillconvert is returning and 
the possible issue of the bool, it may not be so irrelevant.  When I 
first compiled the sample program in Obj-C, I had a conflicting 
declaration of Bool.  One was in the FreeTDS header and the other was in 
the main objective-c header file.  I had added a directive to not 
declare the bool in the FreeTDS header like the other ones were already 
there to avoid redeclaring it.  What I added in the FreeTDS header was 
to the end of the !defined parts for the bool was as follows.  This 
allowed the program to compile without any errors.

&& !defined(OBJC_BOOL_DEFINED)


But what made me think of it now, is that objc.h declared the bool 
differently than FreeTDS.  This to me is most likely the issue in Obj-C 
with dbwillconvert.

FreeTDS defines the bool as         typedef int                      BOOL;
objc.h defines the bool as              typedef signed char        BOOL; 

I'm not really sure why, but it has this comment 

// BOOL is explicitly signed so @encode(BOOL) == "c" rather than "C"
// even if -funsigned-char is used.

They also later define YES = a Bool of 1 and NO = bool of  0.  I'm not 
sure why or what implications this has other than when a type is 
expected to be one thing and its another, there are obvious issues when 
data is retrived from memory. 


Thanks again for any feedback. 

Joe