Utility::ClassAccessors Class Reference

Get and set properties associated with a native C++ class More...

#include <ClassAccessors.h>

Classes
class	ChildList
class	Property

Public Member Functions
size_t	GetPropertyCount () const
const Property &	GetPropertyByIndex (size_t index) const
size_t	GetChildListCount () const
const ChildList &	GetChildListByIndex (size_t index) const
bool	TryOpaqueGet (void *dst, size_t dstSize, ImpliedTyping::TypeDesc dstType, const void *src, uint64 id, bool stringForm=false) const
template<typename ResultType , typename Type >
bool	TryGet (ResultType &result, const Type &src, uint64 id) const
template<typename ResultType >
bool	TryGet (ResultType &result, const void *src, uint64 id) const
bool	TryOpaqueSet (void *dst, uint64 id, const void *src, ImpliedTyping::TypeDesc srcType, bool stringForm=false) const
bool	TryOpaqueSet (void *dst, uint64 id, size_t arrayIndex, const void *src, ImpliedTyping::TypeDesc srcType, bool stringForm=false) const
template<typename Type >
bool	TryOpaqueSet (Type &dst, uint64 id, const void *src, ImpliedTyping::TypeDesc srcType, bool stringForm=false) const
template<typename ValueType , typename Type >
bool	TrySet (const ValueType &valueSrc, Type &dst, uint64 id) const
std::pair< void *, const ClassAccessors * >	TryCreateChild (void *dst, uint64 childListId) const
template<typename Type >
std::pair< void *, const ClassAccessors * >	TryCreateChild (Type &dst, uint64 childListId) const
template<typename GetFn , typename SetFn >
void	Add (const utf8 name[], GetFn &&getter, SetFn &&setter, size_t fixedArrayLength=1)
template<typename ChildType , typename CreateFn , typename GetCountFn , typename GetByIndexFn , typename GetByKeyFn >
void	AddChildList (const utf8 name[], CreateFn &&, GetCountFn &&, GetByIndexFn &&, GetByKeyFn &&)
	ClassAccessors (size_t associatedType)

Protected Member Functions
Property &	PropertyForId (uint64 id)

Protected Attributes
size_t	_associatedType
VariantFunctions	_getters
VariantFunctions	_setters
std::vector< std::pair< uint64, Property > >	_properties
std::vector< std::pair< uint64, ChildList > >	_childLists

Detailed Description

Get and set properties associated with a native C++ class

This class is designed to facilite interaction between a native class and data. For a class type, we can define get and set operations, with a given string name. The system can use these properties for serialisation tasks (as well as binding to data in various ways.

To use this system, classes must define a specialisation of GetAccessors<Type>(). That exposes a list of get and set operations to the system. Typically these get and set operations will use the default implementations. But sometimes custom functionality can be provided for special types.

Here is a typical implementation of GetAccessors<>()

@code 
            class Rect2D
            {
                UInt2 _topLeft, _bottomRight;
//              friend const ClassAccessors& GetAccessors<Rect2D>();
            };
   
            template<> const ClassAccessors& GetAccessors<Rect2D>()
            {
                static ClassAccessors accessors(typeid(Rect2D).hash_code());
                static bool init = false;
                if (!init) {
                    accessors.Add(
                        u("TopLeft"), 
                        DefaultGet(Rect2D, _topLeft),
                        DefaultSet(Rect2D, _topLeft));
                    accessors.Add(
                        u("BottomRight"), 
                        DefaultGet(Rect2D, _bottomRight),
                        DefaultSet(Rect2D, _bottomRight));
                    accessors.Add(
                        u("Size"), 
                        [](const Rect2D& r) { return UInt2(r._bottomRight - r._topLeft); },
                        nullptr);
                    init = true;
                }
                return accessors;
            };
        \endcode

Notice that some accessors provide access to a member. The "Size" accessor has a special case "get" implementation. We could have provided a "set" for "Size" as well – but in this case it's ommitted.

Classes with registered accessors can be used with the AccessorSerialize and AccessorDeserialize functions. These can load and save these types automatically.

This system is particularly useful for types that require multiple different types of serialisation methods (or multiple data-based ways to interact with them). For example, the editor performs string based get and sets on native types. At the same type, we may want to have separate code to load and save those types from disk. This is a perfect type to use class accessors.

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The documentation for this class was generated from the following files:

• Utility/Meta/ClassAccessors.h
• Utility/Meta/ClassAccessors.cpp
• Utility/Meta/ClassAccessorsImpl.h