wxAnyValueType Class Reference

#include <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

See Also

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.

Constructor & Destructor Documentation

wxAnyValueType::wxAnyValueType

(

)

Default constructor.

virtual wxAnyValueType::~wxAnyValueType ( )

virtual

Destructor.

Member Function Documentation

template<typename T >

bool wxAnyValueType::CheckType

(

)

const

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

Remarks

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.

See Also

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.