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Subject: Re: [tarantool-patches] Re: [PATCH] decimal: add methods truncate and
 set_scale
From: Serge Petrenko <sergepetrenko@tarantool.org>
In-Reply-To: <20190719115746.GA29078@atlas>
Date: Fri, 19 Jul 2019 15:15:11 +0300
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Message-Id: <B524BCAA-4C58-45B9-A768-6E3A0F9BC85F@tarantool.org>
References: <20190719112136.23483-1-sergepetrenko@tarantool.org>
 <20190719115746.GA29078@atlas>
To: Konstantin Osipov <kostja@tarantool.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>, tarantool-patches@freelists.org
List-ID: <tarantool-patches.dev.tarantool.org>


> 19 =D0=B8=D1=8E=D0=BB=D1=8F 2019 =D0=B3., =D0=B2 14:57, Konstantin =
Osipov <kostja@tarantool.org> =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0=D0=BB(=D0=
=B0):
>=20
> * Serge Petrenko <sergepetrenko@tarantool.org> [19/07/19 14:42]:
>> This patch adds 2 methods to decimal library and lua module:
>> truncate will remove all trailing fractional zeros and set_scale will
>> either perform rounding or append excess fractional zeros.
>>=20
>=20
> Please note that it is Trim in the ldec library.
> truncate() has a slightly different meaning.
>=20
>> +decimal_t *
>> +decimal_truncate(decimal_t *dec)
>> +{
>> +	decimal_t *res =3D decNumberTrim(dec);
>> +
>> +	/* No errors are possible */
>> +	assert(res =3D=3D dec);
>> +	return res;
>> +}
>> +
>> +decimal_t *
>> +decimal_set_scale(decimal_t *dec, int scale)
>> +{
>> +	if (scale < 0)
>> +		return NULL;
>> +	if (scale <=3D decimal_scale(dec))
>> +		return decimal_round(dec, scale);
>> +	/* how much zeros shoud we append. */
>> +	int delta =3D scale + dec->exponent;
>> +	if (scale > DECIMAL_MAX_DIGITS || dec->digits + delta > =
DECIMAL_MAX_DIGITS)
>> +		return NULL;
>> +	decimal_t new_scale;
>> +	decimal_from_int64(&new_scale, -scale);
>> +	decNumberRescale(dec, dec, &new_scale, &decimal_context);
>> +	assert(decimal_check_status(dec, &decimal_context) !=3D NULL);
>> +	return dec;
>=20
> Please also note here: the name is rescale(), not set_scale(). The
> meaning of set_scale() is slightly different.
>=20
> Please use less confusing names.

Hi! Thank you for review.
No problem, renamed to trim() and rescale().
The changes are on the branch.

>=20
> otherwise lgtm.
>=20
> --=20
> Konstantin Osipov, Moscow, Russia
>=20


--
Serge Petrenko
sergepetrenko@tarantool.org