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Date: Wed, 3 Mar 2021 12:06:43 +0100
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Message-ID: <9BF1EB68-3F1F-4FBF-A87F-FADF98B09E4A@9dev.de>
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 <09ef54b2-a6b1-5bf5-8562-f2f436fd4d92@processus.org>
To: Pierre <pierre-php@processus.org>
Subject: Re: [PHP-DEV] Add __toString() to DateInterval
From: m@9dev.de (Moritz Friedrich)

Am 03.03.2021 um 11:53 schrieb Pierre <pierre-php@processus.org>:
>=20
> Le 03/03/2021 =C3=A0 11:37, Moritz Friedrich a =C3=A9crit :
>> Hi internals,
>> I=E2=80=99ve been active in the PHP ecosystem as @Radiergummi for =
quite a while now, but not on internals yet, so: nice to meet you all!
>>=20
>> I would like to propose adding a `__toString()` method to the =
`DateInterval` class that should return a valid ISO8601 interval =
(https://en.wikipedia.org/wiki/ISO_8601#Time_intervals). As it stands, =
the class supports creating instances from such interval strings passed =
to its constructor, but the reverse isn=E2=80=99t true: The only way to =
build a string representation of the interval is by querying the =
`DateInterval::format` method for the individual durations multiple =
times (see =
https://stackoverflow.com/questions/33787039/format-dateinterval-as-iso860=
1#answers for examples).
>>=20
>> Allowing to cast `DateInterval`s to strings would make the most sense =
in my opinion, and probably doesn=E2=80=99t break BC. Use cases include =
communicating with other APIs that work with ISO8601, or persistence of =
periods in databases, for example.
>>=20
>> So instead of the following:
>>=20
>>     function formatDateInterval(DateInterval $interval, string =
$default =3D 'PT0S'): string {
>>         return rtrim(str_replace(
>>             ['M0S', 'H0M', 'DT0H', 'M0D', 'P0Y', 'Y0M', 'P0M'],
>>             ['M', 'H', 'DT', 'M', 'P', 'Y', 'P'],
>>             $interval->format('P%yY%mM%dDT%hH%iM%sS')
>>         ), 'PT') ?: $default;
>>     }
>>          formatDateInterval(new DateInterval('P1DT5H')) =3D=3D=3D =
'P1DT5H'
>>=20
>> I=E2=80=99d like to be able to do this:
>>=20
>>     (string)new DateInterval('P1DT5H') =3D=3D=3D 'P1DT5H'
>>=20
>> Following alternative approaches come to mind:
>>=20
>> 1. Adding a new, specialized method to the class (eg. =
`DateInterval::toIsoString(): string`):
>>    While being the most BC-safe option, this would be completely =
different to the rest of the PHP date APIs.
>>=20
>> 2. Adding a new interval format constant to be passed to =
`DateInterval::format` (eg. `DATE_INTERVAL_ISO8601`):
>>    Most in line with the `DateTime` API, but probably requires =
special case handling in `format` code.
>>=20
>> =46rom those, having `__toString` seems most desirable to me.
>> While I=E2=80=99m not proficient with C, I=E2=80=99d really like to =
see this implemented and would gladly help out where I can. Might =
someone be able to advise?
>>=20
>>=20
>> Sincerely
>> Moritz / Radiergummi
>=20
> Hello,
>=20
> I don't like implicit __toString() methods, they have to be very =
carefully documented and it's "magic". Wouldn't it be best to have both =
the `toIsoString()` and `__toString()` (as a fallback) methods ?
>=20
> Having the constant is a good idea too, it would make it probably more =
consistent with the DateTime class, I'm not opposed having three =
variations to do skin the same cat.
>=20
> Regards,
>=20
> Pierre
>=20
> --=20
> PHP Internals - PHP Runtime Development Mailing List
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>=20

Hi Pierre,

Having `__toString` proxy to `toIsoString` internally sounds like a good =
idea, but I=E2=80=99m not too fond of the constant - all other built-in =
date constants translate to a string of plain format characters, which =
isn=E2=80=99t possible in this case, so it would be meaningless =
everywhere else.

Sincerely,
Moritz