Re: Ternary associativity

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]