On 23/07/2020 13:26, Nikita Popov wrote:
PHP currently has an incorrect right-associative ternary operator. In
https://wiki.php.net/rfc/ternary_associativity the use of nested ternaries
was deprecated, and was supposed to become an error in PHP 8.0.
Concurrently with that proposal
https://wiki.php.net/rfc/concatenation_precedence made a very similar
change to the concatenation operator precedence. The difference here is
that this throws a deprecation notice in PHP 7.4 (same), but changes the
behavior in PHP 8.0 (rather than making it an error).
If anything, I would argue for making both of these into errors, if
that's possible. I think the biggest risk with this kind of change is
not existing code relying on the old behaviour, it is code relying on
the *new* behaviour which is accidentally run on older versions of PHP.
To give a real-life example, libraries that supported PHP 5.3 sometimes
received patches containing the short array syntax introduced in 5.4.
Since few projects have perfect test coverage and CI builds against
multiple targets, these might end up in tagged releases. They were soon
spotted by 5.3 users, because they caused a fatal error.
A similar mistake involving concatenation or ternary precedence (with
code tested on 8.x and run on 7.x) would lead to much subtler bugs, and
might go undetected for longer.
I realise that I am advocating an extra delay here, where I just argued
the opposite regarding named parameters. I think the cost-benefit
analysis comes out differently, notably on the benefit side:
- raising an error has significant benefits over the current behaviour,
since it makes mistakes easier to spot
- the remaining benefit of the full change is only a mild convenience,
since the behaviour can be achieved by adding parentheses
Regards,
--
Rowan Tommins (né Collins)
[IMSoP]
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