Re: ECPG and C++ compilation

On Mon, 2003-02-24 at 09:24, Michael Meskes wrote:
> On Sat, Feb 22, 2003 at 09:14:43AM -0600, Matthew Vanecek wrote:
> > I don't think that will work. I can never get ecpg to recognize
> > typedefed structs, even when declaring the typedefed struct within a
> > DECLARE SECTION.
>
> Now that I do not understand. What exactly doesn't work? do you have a
> small example?
>

#include <stdio.h>

EXEC SQL BEGIN DECLARE SECTION;
struct s_somestruct {
int id;
char *field;
};

typedef struct s_somestruct SomeStruct;
EXEC SQL END DECLARE SECTION;

int main(int argc, char **argv)
{
printf("this is just to show parse errors from ecpg\n");
return 0;
}

yields:

me2v(at)reliant conn $ ecpg example.pgc
example.pgc:7: ERROR: parse error at or near ";"

If instead I use:

#include <stdio.h>

struct s_somestruct {
int id;
char *field;
};

EXEC SQL BEGIN DECLARE SECTION;
typedef struct s_somestruct SomeStruct;
EXEC SQL END DECLARE SECTION;

int main(int argc, char **argv)
{
printf("this is just to show parse errors from ecpg\n");
return 0;
}

I get:
me2v(at)reliant conn $ ecpg example.pgc
example.pgc:9: ERROR: parse error at or near "SomeStruct"

I get this error also if I use:

EXEC SQL BEGIN DECLARE SECTION;
struct s_somestruct {
int id;
char *field;
} a_struct;

typedef struct s_somestruct SomeStruct;
EXEC SQL END DECLARE SECTION;

Doing "typedef struct { /* stuff */ } AStruct;" appears to work with
ecpg from 7.3.2, but IIRC, it would not work in 7.2.3.

> > Probably doing the sizeof calculation within ecpg would be the proper
> > way to go, and using that value in the ECPGdo call instead of
> > sizeof(whatever). With respect to C++, anyhow. I'm sure the developers
>
> But that would mean you cannot precompile on one machine for usage on
> another. Right?
>

Is sizeof() a compile-time execution/calculation? If so, then it would
definitely not be portable, unless you implemented/used a generic types
library (such as glib, for example). Since it works in C, though, and
ECPG generates C, I'm by no means making a suggestion to follow this
path. ;)

--
Matthew Vanecek
perl -e 'print $i=pack(c5,(41*2),sqrt(7056),(unpack(c,H)-2),oct(115),10);'
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