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Date: Wed, 10 Jul 2019 23:37:38 +0200
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To: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] [RFC] Strict operators directive
From: arnold.adaniels.nl@gmail.com (Arnold Daniels)

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Hi Nikita,

Thanks for your feedback.

I'll fix the textual errors you mentioned.

* "To compare two numeric strings as numbers, they need to be cast to
> floats." This may loose precision for integers. It is better to cast to
> numbers (int or float) using, with the canonical way being +$x. But I guess
> that won't work under strict_operators. Maybe we should have a (number)
> cast (it already exists internally...)
>

Good point. While in most cases you know if you're working with floats or
integers, adding a way to cast to either an int or float would be nice.
Maybe preferably through a function like `numberval($x)` or simply
`number($x), so the `(type)` syntax is reserved for actual types. That
would be an RFC on its own though.


> * This has already been mentioned by others: Having $str1 < $str2 perform
> a strcmp() style comparison under strict_operators is surprising. I think
> that overall the use of lexicographical string comparisons is quite rare
> and should be performed using an explicit strcmp() call. More likely than
> not, writing $str1 < $str2 is a bug and should generate a TypeError. Of
> course, equality comparisons like $str1 == $str2 should still work, similar
> to the distinction you make for arrays.
>

Ok, fair. I'll change it so <,<=,>,>=,<=> comparison on a string throws a
TypeError, similar to arrays, resources, and objects.


> * If I understand correctly, under this RFC "foo" == 0 will throw a
> TypeError, but ["foo"] == [0] will return false. Generally the behavior of
> the recursive comparison here is that it's the same as strict == but all
> errors become not-equal instead. Correct? I'm not sure how I feel about
> this, as it seems to introduce one more set of semantics next to the weak
> ==, strict == and === semantics there already are.
>

The syntax would be `$a == $b` (or `$a == [0]`), where $a and $b are a
string/int in one case and both an array in the other case. In the second
case, we can't throw a TypeError as both operands are of the same type.


> * I also find it somewhat odd that you can't write something like "$obj !=
> null" anymore, only "$obj !== null".
>

To check against null, it's better to use !==. For objects (and resources)
using `!= null` is ok, but for other types, it's currently not. For
example; `[] == null` gives true.


> * I think the "solution" to the last three points is a) only support
> numbers in relational operators (<,<=,>,>=,<=>) and throw TypeErrors
> otherwise (maybe modulo provisions for object overloading) and b) allow
> comparing any types in == and !=, without throwing a TypeError. The
> question "Are 42 and 'foobar' equal?" has a pretty clear answer: "No they
> aren't", so there is no need to make this a TypeError (while the question
> "Is 42 larger than 'foobar'?" has no good answer.) I believe doing
> something like this would roughly match how Python 3 works. (Edit: I see
> now that this is mentioned in the FAQ, but I think it would be good to
> reconsider this. It would solve most of my problems with this proposal.)
>

Besides the argument in the FAQ, having the == and != return do a type
check, means there are a lot more cases where the behavior changes rather
than that a TypeError is thrown. Currently `"foobar" == 0` returns true,
but this would make it return false. So would `1 == true`, `"0" == 0` and
`"0" == false`. To reduce the cases where the behavior changes to a
minimum, it's better to throw TypeErrors for == and !=.


> * String increment seems like a pretty niche use case, and I believe that
> many people find the overflow behavior quite surprising. I think it may be
> better to forbid string increment under strict_operators.
>

Ok


> * A similar argument can be made for the use of &, | and ^ on strings.
> While I have some personal fondness for these, in practical terms these are
> rarely used and may be indicative of a bug. I think both for string
> increment and string and/or/xor it may be better to expose these as
> functions so their use is more explicit.
>

These operators make it very easy to work with binary data as strings in
PHP. In other languages you have to work with byte arrays, which is a major
pain. They're also very intuitive; `"wow" & "xul"` is the same as
`chr(ord('w') & ord('x')) . chr(ord('o') & ord('u')). chr(ord('w') &
ord('l'))`. I think these should stay.


>
> Regards,
> Nikita
>

Arnold

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