wxAnyValueType Class Reference

#include </home/zeitlin/src/wx/github/interface/wx/any.h>

---

Detailed Description

wxAnyValueType is base class for value type functionality for C++ data types used with wxAny.

Usually the default template will create a satisfactory wxAnyValueType implementation for a data type, but sometimes you may need to add some customization. To do this you will need to add specialized template of wxAnyValueTypeImpl<>. Often your only need may be to add dynamic type conversion which would be done like this:

        template<>
        class wxAnyValueTypeImpl<MyClass> :
            public wxAnyValueTypeImplBase<MyClass>
        {
            WX_DECLARE_ANY_VALUE_TYPE(wxAnyValueTypeImpl<MyClass>)
        public:
            wxAnyValueTypeImpl() :
                wxAnyValueTypeImplBase<MyClass>() { }
            virtual ~wxAnyValueTypeImpl() { }

            virtual bool ConvertValue(const wxAnyValueBuffer& src,
                                      wxAnyValueType* dstType,
                                      wxAnyValueBuffer& dst) const
            {
                // GetValue() is a static member function implemented
                // in wxAnyValueTypeImplBase<>.
                MyClass value = GetValue(src);

                // TODO: Convert value from src buffer to destination
                //       type and buffer. If cannot be done, return
                //       false. This is a simple sample.
                if ( dstType->CheckType<wxString>() )
                {
                    wxString s = value.ToString();
                    wxAnyValueTypeImpl<wxString>::SetValue(s, dst);
                }
                else
                {
                    return false;
                }
            }
        };

        //
        // Following must be placed somewhere in your source code
        WX_IMPLEMENT_ANY_VALUE_TYPE(wxAnyValueTypeImpl<MyClass>)

wxAnyValueTypeImplBase<> template, from which we inherit in the above example, contains the bulk of the default wxAnyValueTypeImpl<> template implementation, and as such allows you to easily add some minor customization.

If you need a have complete control over the type interpretation, you will need to derive a class directly from wxAnyValueType, like this:

        template <>
        class wxAnyValueTypeImpl<MyClass> : public wxAnyValueType
        {
            WX_DECLARE_ANY_VALUE_TYPE(wxAnyValueTypeImpl<MyClass>)
        public:
            virtual void DeleteValue(wxAnyValueBuffer& buf) const
            {
                // TODO: Free the data in buffer
                // It is important to clear the buffer like this
                // at the end of DeleteValue().
                buf.m_ptr = NULL;
            }

            virtual void CopyBuffer(const wxAnyValueBuffer& src,
                                    wxAnyValueBuffer& dst) const
            {
                // TODO: Copy value from one buffer to another.
                //       dst is already uninitialized and does not
                //       need to be freed.
            }

            virtual bool ConvertValue(const wxAnyValueBuffer& src,
                                      wxAnyValueType* dstType,
                                      wxAnyValueBuffer& dst) const
            {
                // TODO: Convert value from src buffer to destination
                //       type and buffer.
            }

            //
            // Following static functions must be implemented
            //

            static void SetValue(const T& value,
                                 wxAnyValueBuffer& buf)
            {
                // TODO: Store value into buf.
            }

            static const T& GetValue(const wxAnyValueBuffer& buf)
            {
                // TODO: Return reference to value stored in buffer.
            }
        };

        //
        // Following must be placed somewhere in your source code
        WX_IMPLEMENT_ANY_VALUE_TYPE(wxAnyValueTypeImpl<MyClass>)

Library:  wxBase

Category:  Data Structures

参照:

wxAny

Public Member Functions
	wxAnyValueType ()
	Default constructor.
virtual	~wxAnyValueType ()
	Destructor.
template<typename T >
bool	CheckType () const
	Use this template function for checking if wxAnyValueType represents a specific C++ data type.
virtual bool	ConvertValue (const wxAnyValueBuffer &src, wxAnyValueType *dstType, wxAnyValueBuffer &dst) const =0
	Convert value into buffer of different type.
virtual void	CopyBuffer (const wxAnyValueBuffer &src, wxAnyValueBuffer &dst) const =0
	Implement this for buffer-to-buffer copy.
virtual void	DeleteValue (wxAnyValueBuffer &buf) const =0
	This function is called every time the data in wxAny buffer needs to be freed.
virtual bool	IsSameType (const wxAnyValueType *otherType) const =0
	This function is used for internal type matching.

List of all members.

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Constructor & Destructor Documentation

wxAnyValueType::wxAnyValueType

(

)

Default constructor.

virtual wxAnyValueType::~wxAnyValueType

(

)

[virtual]

Destructor.

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Member Function Documentation

template<typename T >

bool wxAnyValueType::CheckType

(

)

const

Use this template function for checking if wxAnyValueType represents a specific C++ data type.

注意:

This template function does not work on some older compilers (such as Visual C++ 6.0). For full compiler compatibility please use wxANY_VALUE_TYPE_CHECK_TYPE(valueTypePtr, T) macro instead.

参照:

wxAny::CheckType()

virtual bool wxAnyValueType::ConvertValue	(	const wxAnyValueBuffer &	src,
		wxAnyValueType *	dstType,
		wxAnyValueBuffer &	dst
	)		const [pure virtual]

Convert value into buffer of different type.

Return false if not possible.

virtual void wxAnyValueType::CopyBuffer	(	const wxAnyValueBuffer &	src,
		wxAnyValueBuffer &	dst
	)		const [pure virtual]

Implement this for buffer-to-buffer copy.

Parameters:

src	This is the source data buffer.
dst	This is the destination data buffer that is in either uninitialized or freed state.

virtual void wxAnyValueType::DeleteValue

(

wxAnyValueBuffer &

buf

)

const [pure virtual]

This function is called every time the data in wxAny buffer needs to be freed.

virtual bool wxAnyValueType::IsSameType

(

const wxAnyValueType *

otherType

)

const [pure virtual]

This function is used for internal type matching.