> Am 11.01.2017 um 14:35 schrieb Nikita Nefedov <inefedor@gmail.com>:
>
> On Wed, 11 Jan 2017 15:07:39 +0300, Dmitry Stogov <dmitry@zend.com> wrote:
>
>> Hi,
>>
>>
>> I propose to introduce a unified type representation (zend_type).
>>
>> Now it's going to be used for typing of arguments and return values.
>>
>> Later we should use it for properties and other things.
>>
>>
>> https://gist.github.com/dstogov/1b25079856afccf0d69f77d499cb0ab1
>>
>>
>> The main changes are in zend_types.h and zend_compile.h, the rest is just an adoption for new type representation.
>>
>> I don't think we need RFC, because this is just an internal change that doesn't change behavior.
>>
>>
>> I got the idea working on typed properties together with Bob and Joe.
>>
>> https://github.com/php/php-src/compare/master...bwoebi:typed_ref_properties
>>
>> I think it would be better to introduce zend_type and then continue work on typed properties.
>>
>>
>> Any comments?
>>
>>
>> Thanks. Dmitry.
>>
>>
>
> Hey Dmitry,
>
> Having worked on callable prototypes I'd say unifying PHP types in Zend
> is something we urgently need for PHP to continue evolving.
>
> I'm not sure if PHP have ever been compatible with less-than-32bit
> archs but if it was I think it should be said that this would break
> such compatibility though.
PHP itself uses more than 2^16 bytes of memory… And we anyway have some code assuming that sizeof(void *) is a power of two. Hence we'll anyway need at least 32 bit.
> It would be great if there were some comment in the code near zend_type
> declaration where you'd explain how it is used and how additional
> data is being added to the pointer.
That's what the ZEND_TYPE_ENCODE_*() macros are for?
> Is there any use of ZEND_TYPE_CE() macro? It seems to be forgotten there?
Not necessarily in this patch, but in typed_ref_property branch reference types use the CE directly.
> If I understood this correctly, the layout of zend_type is as follows:
>
> [xxxx xxxx xxxx xxxx] xxxx xxxx xxxx xxy0 - for IS_OBJECT type hint
> where the `xxxx`s are a (zend_string *) pointer and `y` designates
> an allow_null flag
>
> [xxxx xxxx xxxx xxxx] xxxx xxxx xxxx xxy1 - for all other type hints
> where the `xxxx`s are a IS_CALLABLE, _IS_BOOL, IS_LONG, IS_DOUBLE,
> IS_STRING or IS_ARRAY
correct.
> Do we decide here that IS_REF modifier should belong to the concrete
> usages of the type (e.g. referentiality is a property of a variable
> and not of a type)?
> I'm not sure this if is a right decision or not but I feel like this
> question should be raised. It is usually the opposite in other languages.
We nowhere user-facing consider references to be a separate type, just internally for the zval representation (which was is_ref in PHP 5) - and as such being a reference is a property of the variable.
> How would you plan to extend this further? Let's say at some point we
> will have callable prototypes or generic classes: we will need to encode
> somehow this type into zend_type: `callable(A)` or `A<Foo>`.
> Even right now it might be useful (as you suggest with ZEND_TYPE_CE)
> to store a (zend_class_entry *) instead of (zend_string *) when
> it is known to us in the zend_type.
> Seems like without extending zend_type to the size of two pointers
> it almost isn't doable :\
> Or, it could be made that zend_type, when it's not a simple type hint,
> would point to the `zend_type_complex` which would store a
> zend_class_entry pointer (or not, if it's for callable) and an array
> of type specifiers. But that introduces another indirection.
zend_type is just a typedef. If needed in future we may define it to occupy 2 * sizeof(void *) or such, just as we'll need it.
The goal of the patch is making type encoding transparent and handleable in a single place.
The current way of adding a new class of types usually was adding a new element to the relevant structs or similar hacks…
Bob