Was deprecation of DATE_RFC7231 and DateTimeInterface::RFC7231 a mistake? View as Markdown

Hi,

I was one of the yes-voters for the
https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_date_rfc7231_and_datetimeinterfacerfc7231
however, I would like to change my vote to no now.

The explanation for the deprecation wasn't very clear, and I feel I
was slightly misled by it. It claims that the constant was
implemented by mistake, but I don't think that was the case.

DATE_RFC7231 follows the timestamp specification from the HTTP format.
It has been repeated by the current RFC 9110
https://www.rfc-editor.org/rfc/rfc9110#section-5.6.7 The GMT part
isn't a mistake; it's hardcoded as part of the format. Thus, the
constant is implemented correctly in PHP.

No, it wasn't. It would format according to local time and just add
"GMT" to the end:
https://www.php.net/manual/en/class.datetimeimmutable.php (docs haven't
been updated for it).

It's true that this could lead to unexpected results when you format a
DateTime that isn't in UTC, but that's a programmer mistake and not
the fault of the constant. The format is timezone agnostic so it's the
responsibility of the programmer to ensure the DateTime object is in
UTC before formatting.

Formatters are only for local time, and do not currently have the
possibility to change the timezone to UTC. So I disagree, as people
rightfully should have expected PHP to handle a specific pre-cooked
format to behave as the RFC that is named after ought to behave.

Users are now faced with having to replace the constant with its
string value, despite the constant having a well-defined use and
producing correct and "wanted" results. This is more error-prone than
accidentally forgetting to call setTimezone(DateTimeZone::UTC).
Deprecating this constant hasn't improved anything for PHP users and
only made things worse.

What do you think? Should we undeprecate these constants?

No, I don't believe we should put them back as they were.

I can think of two possible ways:

1. We could think about adding specific formatting methods, such as
   "asRfc7231String()".

   This would allow for it to handle the timezone "fix" and also return the
   right format. Constants aren't the way forwards here. But that also means,
   that we probably should have methods for other useful formats /
   specifications too.

2. Create a new formatting specifier which has a specfic meaning to set the
   timezone to UTC when used at the beginning of the string, say "-".

   There is some precedent with special formatting letters with
   DateTimeImmutable::createFromFormat.

   The constant value then could be "-D, d M Y H:i:s \G\M\T"

I don't really like either of these though.

cheers,
Derick

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Hey all

Hi All,

I was one of the yes-voters for the
https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_date_rfc7231_and_datetimeinterfacerfc7231
however, I would like to change my vote to no now.

The explanation for the deprecation wasn't very clear, and I feel I
was slightly misled by it. It claims that the constant was
implemented by mistake, but I don't think that was the case.

DATE_RFC7231 follows the timestamp specification from the HTTP format.
It has been repeated by the current RFC 9110
https://www.rfc-editor.org/rfc/rfc9110#section-5.6.7
The GMT part isn't a mistake; it's hardcoded as part of the format.
Thus, the constant is implemented correctly in PHP.

It's true that this could lead to unexpected results when you format a
DateTime that isn't in UTC, but that's a programmer mistake and not
the fault of the constant. The format is timezone agnostic so it's the
responsibility of the programmer to ensure the DateTime object is in
UTC before formatting.
While most of the time being the same, there are some very distinct
differences between GMT and UTC. As RFC7231 explicitly requests GMT I'd
even reject formatting a DateTime-object that has been set to UTC.

IMO if someone relies upon it, they can very easily create a userland
piece of code that formats any DateTimeImmutable correctly as RFC7231
date like in https://3v4l.org/WZv34#v8.4.14

That is much easier and will always get the user the result they want.
Adding such a function for each and every edge-case to the PHP-Core
seems overkill.

Users are now faced with having to replace the constant with its
string value, despite the constant having a well-defined use and
producing correct and "wanted" results. This is more error-prone than
accidentally forgetting to call setTimezone(DateTimeZone::UTC).
Deprecating this constant hasn't improved anything for PHP users and
only made things worse.

What do you think? Should we undeprecate these constants?
Nope! But add a comment to the deprecation information on the docs at
PHP.net

My 0.02€

Cheers

Andreas

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