Re: Assert for frontend programs?

Andrew Dunstan <andrew(at)dunslane(dot)net> writes:
> As I'm working through the parallel dump patch, I notice this in one of
> the header files:

> #ifdef USE_ASSERT_CHECKING
> #define Assert(condition) \
> if (!(condition)) \
> { \
> write_msg(NULL, "Failed assertion in %s, line %d\n", \
> __FILE__, __LINE__); \
> abort();\
> }
> #else
> #define Assert(condition)
> #endif

> I'm wondering if we should have something like this centrally (e.g. in
> postgres_fe.h)? I can certainly see people wanting to be able to use
> Assert in frontend programs generally, and it makes sense to me not to
> make everyone roll their own.

+1, especially if the hand-rolled versions are likely to be as bad as
that one (dangling else, maybe some other issues I'm not spotting
in advance of caffeine consumption). I've wished for frontend Assert
a few times myself, but never bothered to make it happen.

Although I think we had this discussion earlier and it stalled at
figuring out exactly what the "print error" part of the macro ought
to be. The above is obviously pg_dump-specific. Perhaps
fprintf(stderr,...) would be sufficient, though -- it's not like
tremendous user friendliness ought to be necessary here.

Also, I think the message really has to include some string-ified
version of the assertion condition --- the line number alone is pretty
unhelpful when looking at field reports of uncertain provenance.

BTW, I think psql already has a "psql_assert".

regards, tom lane