> On 15/04/2016, at 9:40 AM, Sara Golemon <poll...@php.net> wrote:
>
> On Thu, Apr 14, 2016 at 3:37 AM, Davey Shafik <da...@php.net> wrote:
>> Whitespace inside of { } should not matter, the contents should be evaluated
>> as an expression and it's results used to determine the variable name, so
>> ${great} should also be $my as in the other cases.
>>
> Right. Which is why I'm conflicted on bug/not-bug/different-bug.
>
> IMO, the label inside ${...} should either always be a variable name
> (like HHVM handles it), or always be an expression. What we have is
> "It's always an expression except in the one specific case of it being
> a valid variable name, in which case that takes precedence. Since the
> versions containing spaces aren't valid variable names, they fall back
> on the more general expression handling.
>
> So I'd be inclined to say "That exception to the rule is the problem",
> except that this is variable interpolation behavior that goes ALL THE
> WAY BACK, and I wouldn't break BC for the world.
>
> So the question becomes: What's the right move going forward. My
> inclination would be to either:
> A: Ignore surrounding whitespace within the ${...} expression.
> Essentially, adopt HHVM's output for these examples.
> B: Throw an error on surrounding whitespace. This will make
> discovering timebombs like these in existing code easier to catch.
>
> In either case, if the programmer actually did want the
> constant->variable double-interpolation, that could be easily achieved
> via "${(foo)}" which disambiguated foo as a variable name from foo as
> an expression.
>
> -Sara
>
>> Is this related to the use of quotes around string array keys inside
>> strings?
>>
>> e.g. "$foo[great]" does not evaluate to $foo['my'] but to $foo['great'].
>>
> I don't think so... I have a feeling that's yet another weird oddity
> to PHP parsing that's waiting to bite us in new and surprising ways.
>
> -Sara
When not inside a string, the inside of the ${...} is always treated as an
expression, by both PHP and HHVM (https://3v4l.org/i2kOP), so that looks like
the
“correct” handling for inside a string.
There is also differing behaviour in PHP when using array access, depending on
if
the label starts with a space or not (https://3v4l.org/YPXkr). This behaviour is
inconsistent with not using array access. HHVM follows the <=PHP5.5 behaviour of
not allowing array access on a constant.
However, there is the massive BC break if the handling inside a string changes
--
Simon Welsh
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