Re: Problems with casting

Jim Nasby <Jim(dot)Nasby(at)BlueTreble(dot)com> writes:
> I've created a variant data type [1]. It seems to work pretty well,
> except for some issues with casting.

> Since the idea of the type is to allow storing any other data type, it
> creates casts to and from all other types. At first these were all
> marked as ASSIGNMENT, but that made using variant with functions quite
> cumbersome. With functions that accepted a variant, you still had to
> explicitly cast it:

> SELECT variant_function( some_field::variant.variant ) FROM some_table;

> I was reluctant to make the casts to variant IMPLICIT, but it seems like
> it actually works rather well... except for arrays:

I suspect that that's only the tip of the iceberg. Remember the mess
we had with implicit casts to text? And those only existed for a dozen
or so types, not for everything. Every function or operator you define
for "variant" is going to be a loaded gun just waiting to shoot your foot
off, if you make all those casts implicit.

regards, tom lane