Re: [HACKERS] Add Roman numeral conversion to to_number

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От David Fetter
Тема Re: [HACKERS] Add Roman numeral conversion to to_number
Дата
Msg-id 20170917164331.GA20718@fetter.org
обсуждение исходный текст
Ответ на Re: [HACKERS] Add Roman numeral conversion to to_number  (Douglas Doole <dougdoole@gmail.com>)
Ответы Re: [HACKERS] Add Roman numeral conversion to to_number  (Chris Travers <chris.travers@adjust.com>)
Список pgsql-hackers
On Sat, Sep 16, 2017 at 10:42:49PM +0000, Douglas Doole wrote:
> Oliver, I took a look at your tests and they look thorough to me.
> 
> One recommendation, instead of having 3999 separate selects to test every
> legal roman numeral, why not just do something like this:
> 
> do $$
> declare
>     i int;
>     rn text;
>     rn_val int;
> begin
>     for i in 1..3999 loop
>         rn := trim(to_char(i, 'rn'));
>         rn_val := to_number(rn, 'rn');
>         if (i <> rn_val) then
>             raise notice 'Mismatch: i=% rn=% rn_val=%', i, rn, rn_val;
>         end if;
>     end loop;
>     raise notice 'Tested roman numerals 1..3999';
> end;
> $$;
> 
> It's a lot easier to maintain than separate selects.

Why not just one SELECT, as in:

SELECT i, to_char(i, 'rn'), to_number(to_char(i, 'rn'), 'rn');
FROM generate_series(1,3999) i

Best,
David.
-- 
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
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