Re: psql \df choose functions by their arguments

I wrote:
> Greg Sabino Mullane <htamfids@gmail.com> writes:
>> * There seems to be no way (?) to limit the functions returned if they
>> share a common root. The previous incantation allowed you to pull out
>> foo(int) from foo(int, bigint). This was a big motivation for writing this
>> patch.

> Hmm, are you trying to say that a invocation with N arg patterns should
> match only functions with exactly N arguments?  We could do that, but
> I'm not convinced it's an improvement over what I did here.  Default
> arguments are a counterexample.

I had an idea about that.  I've not tested this, but I think it would be
a trivial matter of adding a coalesce() call to make the query act like
the type name for a not-present argument is an empty string, rather than
NULL which is what it gets right now.  Then you could do what I think
you're asking for with

\df foo integer ""

Admittedly this is a bit of a hack, but to me this seems like a
minority use-case, so maybe that's good enough.

As for the point about "int" versus "integer" and so on, I wouldn't
be averse to installing a mapping layer for that, so long as we
did it to \dT as well.

            regards, tom lane