yomm2

yorel::yomm2::policy::rtti
yorel::yomm2::policy::deferred_static_rtti
_{defined in <yorel/yomm2/policy.hpp>, also provided by <yorel/yomm2/core.hpp>, <yorel/yomm2/keywords.hpp>}

struct rtti;

struct deferred_static_rtti : virtual rtti;

A rtti facet provides type information for classes and objects, implements downcast in presence of virtual inheritance, and writes descriptions of types to an ostream-like object.

A deferred_static_rtti, derived from rtti, directs YOMM2 to defer collection of static type information until update is called. This makes it possible to interface with custom RTTI systems that use static constructors to assign type information.

Requirements for implementations of rtti

Name	Description	Required
type_id static_type<T>	return a type_id for T	yes
type_id dynamic_type<T>	return a type_id for an object’s dynamic type	depending on context
void type_name<Stream>	write a description of type_id to a stream	no
unspecified type_index	return a unique key for a type_id	depending on context
D dynamic_cast_ref<D, B>	cast from base class to derived class	if using virtual inheritance

(all members are static)

static_type

template<class Class>
static type_id static_type();

Return a type id for Class.

Template parameters

• Class: a class registered via register_classes or use_classes.

dynamic_type

template<class Class>
static type_id dynamic_type(const Class& obj);

Return a type id for obj. May be omitted if using final virtual_ptrs only. Required.

Template parameters

• Class: a class registered via register_classes or use_classes.

type_name

template<typename Stream>
static void type_name(type_id type, Stream& stream);

Write a description of the class identified by type to stream. Not required. rtti provides a default implementation that prints type_id(type). Implementations should provide a more readable description, if possible.

Template parameters

• Stream: a model of RestrictedOutputStream.

Function parameters

• type: the type id of the class to describe.
• stream: the stream to write the description to.

type_index

static /*unspecified*/ type_index(type_id type);

Return an unspecified object that uniquely identifies a class. Required if static_type can return different type ids for the same class. See std_rtti for an example of this.

Function parameters

• type: the type id of a class

dynamic_cast_ref

template<typename Derived, typename Base>
static Derived dynamic_cast_ref(Base&& obj);

Cast obj to Derived, a subclass of Base. Required if virtual inheritance is used in the registered classes.

Template parameters

• Base: a registered class. Base&& is guaranteed to evaluate to a reference.
• Derived: a registered class, derived from Base.

Function parameters

• obj: the object to cast. to a Base object.

Implementations of rtti

std_rtti	use standard RTTI
minimal_rtti	use static RTTI only

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