[PHP-DEV] Re: RFC karma request: scalar object methods (with a working implementation)

Dne 29.06.2026 v 15:00 Michal Kral napsal(a):
> Hi all,
> 
> I have a complete, tested implementation of scalar object methods — 
> $str->trim(), (3)->pow(2) — and I'd like to write it up as a formal RFC. 
> Could someone grant me wiki RFC karma? The design and the branches are 
> below; I'd genuinely value early reactions while I write it up — 
> especially from anyone who remembers why the 2014 attempt stalled, since 
> this is built specifically to resolve that.
> 
> I know "methods on primitives" was proposed and declined before 
> (Nikita's 2014 "Methods on primitive types in PHP"). The reason it 
> stalled was loose typing: $x->trim() would need a runtime type check and 
> would behave differently depending on what $x held. This proposal 
> sidesteps that entirely, by generalizing the resolution Nikita himself 
> suggested in that thread — requiring an explicit cast where the type 
> isn't already clear.
> 
> The idea: dispatch only on receivers the compiler already knows are 
> scalar. The method call is rewritten at compile time to an ordinary call 
> into an internal backing class — no runtime type dispatch, no new 
> opcode, the object method-call path is untouched. A receiver qualifies 
> only if its type is guaranteed syntactically: a literal, a (string)/ 
> (int) cast, a concatenation/interpolation, a non-nullable scalar-typed 
> property, or a call with a declared non-nullable scalar return type. An 
> untyped $x->trim() is left exactly as today (Error). Crucially, dispatch 
> never depends on optimizer-inferred types, so behaviour is identical 
> with and without opcache.
> 
> echo "  Hello World  "->trim()->upper();   // "HELLO WORLD"
> echo (3)->pow(2);                          // 9
> echo "hello"->length()->pow(2);            // 25 — length():int chains 
> into the int methods
> So the cast Nikita proposed (((string) $num)->chunk()) is only needed 
> where the type isn't already guaranteed; everywhere else the dispatch is 
> sound by construction, with no runtime check.
> 
> It's structured as one proposal with two independent votes:
> 
> Scalar methods on guaranteed free receivers (the above). A pure 
> capability — it adds a way to call scalar operations and changes nothing 
> about untyped code. Proposed initial sets: a small curated Str (trim/ 
> upper/lower/length + contains/startsWith/endsWith), Int (abs/pow/clamp), 
> and Float (round/ceil/floor/abs); bool deliberately gets none (its 
> operations are operators, not methods). The sets are governed by 
> explicit criteria and are the easiest thing to tune in discussion.
> 
> Scalar-typed local variables (int $x = ...;, scalar types only), which 
> additionally make a typed local a guaranteed receiver (string $s = ...; 
> $s->trim()). This is the more contested half — it also carries the 
> "local type discipline" argument — so it's a separate vote: a "no" here 
> ships the capability without typed locals.
> 
> What I'm deliberately NOT doing, up front so it's not a surprise:
> 
> No method-call-result receivers ($this->getName()->trim()) — that would 
> rest on return-type covariance under inheritance; not worth the surface.
> Int::abs/pow return int|float (they can overflow, as the global 
> functions do), so they're honest terminals — they don't chain. 
> (Int::clamp is the one initial int method provably : int for all inputs, 
> so it does chain — no method declares : int while secretly overflowing.)
> No int|false typed locals — that's a sentinel state, not a committed 
> type; ?T is supported, sentinel-unions are not.
> The backing classes are internal-only (NUL-prefixed name, like anonymous 
> classes): class_exists('Str') is false, no Reflection, userland class 
> Str {} can't collide.
> Implementation status — this is built and tested, not a sketch:
> 
> Scalar methods add zero new opcodes — the desugar emits an ordinary 
> static call, and the object method-call path is byte-for-byte unchanged. 
> (Typed locals do add dedicated *_TYPED assignment opcodes, but the 
> untyped hot path stays byte-identical — see the perf point below.)
> Performance (deterministic callgrind, release build): the untyped hot 
> path is byte-identical; the standard bench.php suite is +0.145% 
> instructions, entirely from predicted-not-taken branches in reference 
> opcodes only, with zero added cache misses or branch mispredictions. 
> Untyped code pays effectively nothing.
> References (the objection that sank prior typed-locals attempts) are 
> enforced through every path — =&, by-ref params, array/object/static- 
> prop refs, yield, closure capture, $$name, extract, $GLOBALS, global — 
> via the existing typed-property reference machinery. Leak-checked under 
> stress.
> Correct under JIT in all three modes (interpreter, function, tracing — 
> differential byte-identical output). opcache SHM + file_cache round-trip 
> verified.
> BC impact, measured: an AST scan of the 1,000 most-downloaded Packagist 
> packages (173k+ files, incl. Laravel, Symfony, the AWS SDK, Guzzle, 
> PHPUnit, Doctrine) found zero affected call sites — every guaranteed- 
> scalar method-call site is a fatal error today, so none exist in real 
> code. Userland Str classes (incl. Laravel's Illuminate\Support\Str) 
> coexist with the backing class, verified.
> Branches (PHP 8.6-dev base):
> 
> Primary (scalar methods): https://github.com/kralmichal/php-src/tree/ 
> rfc/scalar-methods
> Secondary (typed locals, stacked): https://github.com/kralmichal/php- 
> src/tree/rfc/typed-locals
> What I'm asking:
> 
> RFC karma, so I can write this up on the wiki.
> Input I'd value while I write it up: does the "compile-time-guaranteed 
> receivers only" framing actually resolve the loose-typing objection for 
> you, or is there a hole I'm not seeing?
> The method-set/naming is the most open part — is a small curated set (a 
> "clean slate" API, distinct from the procedural names) the right call, 
> or a non-starter?
> (I'm not asking you to pre-approve the idea — I'll put the full RFC on 
> the wiki and we can have the real discussion there. This is to get karma 
> and to catch any fatal objection before I do.)
> 
> Thanks for reading, Michal Kral
Sorry forgot wiki username: michalkral