Re: On hardcoded type aliases and typmod for user types

Thread added to TODO.

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Martijn van Oosterhout wrote:
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> Hi,
>
> As part of previous discussions about typmod for user type, Tom
> mentioned that you would need to make type and function names
> equivalent. As it turns out, if you refactor a few rules, you can
> actually make it work and manage them seperately. For this to work the
> current "col_name_keyword" non-terminal has to be divided into few more
> categories. The criterion is mostly whether it is followed by a left
> parenthsis.
>
> 1. Some can be moved to unreserved words, mostly the types BIT, VARCHAR,
> BIGINT etc since they don't need special rules anymore.
>
> 2. Words that have special productions (eg CONVERT, COALESCE etc),
> these can still only be used as column names, not types or
> (user-defined) functions.
>
> 3. Words which can be column names functions but not types. These never
> appear normally with a parenthesis, so they will be interpreted as a
> function if there is one. (eg SETOF, NATIONAL, etc)
>
> 4. Words that can be column names and types but not functions. These
> are artifacts of the grammer due to the fact that VARYING is
> unrestricted. These are BIT, NCHAR, CHAR_P and CHARACTER.
>
> After this, you can have user-functions that take an arbitrary set of
> parameters. There'll need to be a bit of code to verify the arguments.
> It results in a net gain of 15 keywords for functions and about 30 for
> types.
>
> My question is, should users be able to create types schema.int4 and
> schema.integer simultaneously. Currently it allows you but it's not
> handled very well (\dT doesn't list both). Should this be allowed?
> Should aliasing for DEC and DECIMAL -> NUMERIC be done for
> user-defined types?
>
> Have a nice day,
> --
> Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> > Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> > tool for doing 5% of the work and then sitting around waiting for someone
> > else to do the other 95% so you can sue them.
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