Re: What happened to the is_<type> family of functions proposal?

On Tue, Sep 21, 2010 at 11:49 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> I think it would be useful to have a way of testing whether a cast to
>> a given type will succeed.  The biggest problem with the
>> exception-catching method is not that it requires writing a function
>> (which, IMHO, is no big deal) but that exception handling is pretty
>> slow and inefficient.  You end up doing things like... write a regexp
>> to see whether the data is in approximately the right format and then
>> if it is try the cast inside an exception block.  Yuck.
>
> The problem here is that putting the exception handling in C doesn't
> make things any better: it's still slow and inefficient.  And in the
> general case the only way to be sure that a string will be accepted by
> the input function is to try it.

Given the current API, that is true.

--
Robert Haas
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