> Le 16 déc. 2019 à 10:58, George Peter Banyard <girg...@php.net> a écrit :
>
> Greetings internals,
>
> I'm here to get internals's opinion about allowing a string offset to be
> replaced with arbitrary strings.
>
> Since forever strings with more then one byte have been truncated silently
> to one byte. The case with empty string *kinda* was existent but had a
> buggy behaviour (see bug 71572 [1]) and as such has been turned into a
> warning in PHP 7.1.0, and is meant to be promoted to an Error Exception per
> the Reclassifying engine warnings RFC. [2]
> An illustration of both these cases is available on 3v4l.org [3]
> <https://3v4l.org/O0nEM>
>
> I've got an implementation ready as a pull request on GitHub [4] (which
> still needs some polishing for it to make CI happy and fix the various
> leaks).
>
> However, the question is if this behaviour is desirable. Moreover, the
> silent truncation of strings with more than one byte should be changed to
> the same severity as the empty string case; i.e. an Error Exception. This
> seems reasonable due to the possible loss of data.
>
> What ever the decision is, a BC break is to be expected. As code which
> inadvertently tries to assign multiple bytes to an offset will know have
> all those bytes in the string whereas before only the first one was used to
> replace the byte at the designated offset. On the other hand the
> introduction of an Error Exception is obviously a BC break but as it points
> out to some kind of logic error.
> I would assume the impact to be minimal for both of these case.
>
> Any opinions?
>
> Best regards
>
> George Peter Banyard
>
> [1] https://bugs.php.net/bug.php?id=71572
> [2] https://wiki.php.net/rfc/engine_warnings
> [3] https://3v4l.org/O0nEM
> [4] https://github.com/php/php-src/pull/5013
Being able to replace one byte with an arbitrary string does not seem very
useful to me, unless you add the functionality of replacing an arbitrary
substring with an arbitrary string (an equivalent of array_splice() for
strings). Your implementation gives the following potentially surprising result:
<?php
$str = "Hello world";
var_dump(strlen($str)); // 11
$str[0] = "あ"; // replace the first byte with three bytes (assuming source code
is UTF-8-encoded)
$str[0] = "H"; // replace the first byte with one byte
var_dump(strlen($str)); // 13
?>
IMO, the only reasonable thing to do at this point is just emitting a Warning
(or an Error).
—Claude
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