Tom Lane <tgl@sss.pgh.pa.us> writes:
> Greg Stark <gsstark@mit.edu> writes:
>
> > There are other ways of achieving the same thing. Structs containing a union
> > for the subclass fields for example.
>
> Doesn't achieve the same thing, unless you mandate that every part of
> the system use the identical massively-overloaded union struct to refer
> to every node.
Are you saying it's important to preserve the ability for modules to add new
node types without notifying the rest of the code? I thought all the node
types were defined in a single header file currently anyways.
> That would (a) defeat the purpose of extensibility, and (b) make the code
> more error prone not less so (since it'd be notationally easy to refer to a
> field that's not actually present in the given node subtype).
You could use a local pointer to be preserve the existing model of a single
point where the decision is made. That could be encapsulated in a macro that
included an assertion to verify the type tag.
It would be pretty cool to have a type-safe codebase. It just seems like too
an awful lot of work for a mostly aesthetic improvement.
--
greg