welder::rods::pybind11 Namespace Reference

Classes
struct	rod
	The pybind11 rod: a stateless policy type satisfying welder::rod. More...

Functions
template<auto Fn, typename Self, typename BaseCall, typename... Args>
decltype(auto)	override_dispatch (const Self &self, BaseCall &&base_call, Args &&... args)
	Dispatch a captured virtual call to its Python override, else to the C++ base.

Function Documentation

override_dispatch()

template<auto Fn, typename Self, typename BaseCall, typename... Args>

decltype(auto) welder::rods::pybind11::override_dispatch	(	const Self &	self,
		BaseCall &&	base_call,
		Args &&...	args )

Dispatch a captured virtual call to its Python override, else to the C++ base.

The reflection-driven replacement for PYBIND11_OVERRIDE/PYBIND11_OVERRIDE_PURE: the method name (for the Python lookup), the return type, and whether the method is pure are all read from Fn — a reflection of the base virtual — rather than spelled by hand.

self is the trampoline instance viewed as the welded type it is bound under (welder_py_base), not the virtual's declaring class. pybind11's get_override(const T*, name) keys the Python-object lookup off typeid(T) — the static pointer type — so T must be the type the instance is registered as (class_<T, Trampoline, …>). For a virtual type inherits from a base, the declaring class differs from the registered type; casting to the declaring class would look the instance up under the wrong registration and miss the override (C++ would silently see the base implementation). The caller (WELDER_PY_OVERRIDE) casts *this to welder_py_base for exactly this reason.

The base-class fallback is passed in as base_call rather than derived from Fn: splicing a member function into a member access (self.[:Fn:]()) performs a virtual call, which would re-enter the override and recurse. The caller supplies a lambda doing a textually qualified Base::method(...) call, which is non-virtual — matching what PYBIND11_OVERRIDE's cname::fn(...) tail does.

Template Parameters

Fn	a reflection of the base virtual member function.

Parameters

self	the trampoline instance as its registered welded type (for the get_override lookup).
base_call	an invocable performing the qualified base-class call.
args	the forwarded call arguments.

Definition at line 64 of file trampoline.hpp.