Re: string function - "format" function proposal

Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> On Fri, Oct 15, 2010 at 12:55 AM, Itagaki Takahiro
> <itagaki(dot)takahiro(at)gmail(dot)com> wrote:
>> I agree that full-spec sprintf is too complex, but precision and
>> zero-full for numeric types are commonly used. I think someone
>> will ask us "Why don't have numeric formats though we have %s?".

> I think someone might also ask - why are you bothering to create this
> at all? The amount of work that has been put into this is, IMHO, far
> out of proportion to the value of the feature. As Pavel points out,
> we already have perfectly good mechanisms for converting our various
> data types to text. We do not need to invent new ones.

I beg to differ. IMO to_char is a lot closer to the "sucks big-time"
end of the spectrum than the "perfectly good" end of the spectrum:
it's a bad implementation of a crummy design. I think a lot of people
would like to have something closer to sprintf-style formatting.

I think we should go into this with the idea that it might only do 10%
of what sprintf can do initially, but there will be pressure to cover a
lot of the other 90% eventually. So it would be a good idea to ensure
that we don't make any choices that are gratuitously incompatible with
standard sprintf format codes. In particular, I agree with the idea of
using %I not %i for identifiers --- in fact I'd go so far as to suggest
that all specifiers we invent, rather than borrowing from sprintf, be
upper-case.

regards, tom lane