Strict equality operator overloading for the \GMP class

[Rafagd]

Description

The GMP class already enjoys a lot of privileges in regards to having the language operators being overloaded under the hood to behave in a sensible way:

gmp_init(0) + gmp_init(1); // $x = \GMP { 1 }
gmp_init(0) + 1; // $x = \GMP { 1 }
gmp_init(0xFFFF_FFFF) & 1; // 0x1
gmp_init(0) < 1; // true
gmp_init(0) > 1; // false
gmp_init(133) == 133; // true 

This is all good but the strict equality operator is the one that behaves in a weird way. While I do understand it would be bad to have \GMP { 0 } === int { 0 } to be true, I do think it's very odd that gmp_init(0) === gmp_init(0) evaluates to false.

While I do understand they are different objects that have different pointers associated to them, I think this is just an interpreter implementation detail that shouldn't surface to the PHP user.

That kinda shuts down a more useful usage [IMO]: these are both the same number with the same type.

[SakiTakamachi]

If do make such changes, how can we be sure that the GMP objects are exactly the same?

Also, what is the difference between == and ===?

In any case, GitHub issues are not suitable for such discussions, so I encourage you to post your ideas on the mailing list.

[Rafagd]

A GMP object is just a big integer representation of a number, and as such, the identity of one single instance of the object is a bit of a commodity. Any copy of the object that hold the same value is somewhat indistinguishable of another.

Currently $x == $y behaves with the loose integer comparison semantics. If both $x and $y are GMP, true if the value they hold is the same, if one of them is not, it will be converted into GMP implicitly using gmp_init if it's int or string and then compared.

The $x === $y uses the strict comparison semantics, but it uses the standard rules for objects, as in "Are they exactly the same object in memory? then true, otherwise false". Which is a bit of an implementation detail, given most operators are overloaded to pretend GMP is just a normal number.

I'll post it to the mailing list later, I agree it would be a breaking change that requires a proper discussion.

[iluuu1994]

Strict equality is not currently customizable in PHP, even in extensions. There's definitely a larger discussion required for something like this. Coincidentally, I'm working on data classes (i.e. classes as value types) which includes this feature (#13800). GMP would be a good use-case for value type semantics.

[Rafagd]

I'm closing the issue, as it's a subset of the one mentioned by @iluuu1994