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			596 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			TeX
		
	
	
	
	
	
			
		
		
	
	
			596 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			TeX
		
	
	
	
	
	
| %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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| %% Name:        variant.tex
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| %% Purpose:     wxVariant docs
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| %% Author:      wxWidgets Team
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| %% Modified by:
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| %% Created:     01/30/2005
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| %% RCS-ID:      $Id$
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| %% Copyright:   (c) wxWidgets Team
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| %% License:     wxWindows license
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| %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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| 
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| \section{\class{wxVariant}}\label{wxvariant}
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| 
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| The {\bf wxVariant} class represents a container for any type.
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| A variant's value can be changed at run time, possibly to a different type of value.
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| 
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| As standard, wxVariant can store values of type bool, wxChar, double, long, string,
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| string list, time, date, void pointer, list of strings, and list of variants. 
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| However, an application can extend wxVariant's capabilities by deriving from the
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| class \helpref{wxVariantData}{wxvariantdata} and using the wxVariantData form of
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| the wxVariant constructor or assignment operator to assign this data to a variant.
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| Actual values for user-defined types will need to be accessed via the wxVariantData
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| object, unlike the case for basic data types where convenience functions such as
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| \helpref{GetLong}{wxvariantgetlong} can be used.
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| 
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| Pointers to any \helpref{wxObject}{wxobject} derived class can also easily be stored
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| in a wxVariant. wxVariant will then use wxWidgets' built-in RTTI system to set the
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| type name (returned by \helpref{GetType}{wxvariantgettype}) and to perform 
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| type-safety checks at runtime.
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| 
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| This class is useful for reducing the programming for certain tasks, such as an editor
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| for different data types, or a remote procedure call protocol.
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| 
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| An optional name member is associated with a wxVariant. This might be used, for example,
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| in CORBA or OLE automation classes, where named parameters are required.
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| 
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| Note that as of wxWidgets 2.7.1, wxVariant is \helpref{reference counted}{trefcount}. 
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| Additionally, the convenience macros {\bf DECLARE\_VARIANT\_OBJECT} and 
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| {\bf IMPLEMENT\_VARIANT\_OBJECT} were added so that adding (limited) support 
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| for conversion to and from wxVariant can be very easily implemented without modifying 
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| either wxVariant or the class to be stored by wxVariant. Since assignment operators 
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| cannot be declared outside the class, the shift left operators are used like this:
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| 
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| \begin{verbatim}
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|     // in the header file
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|     DECLARE_VARIANT_OBJECT(MyClass)
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|     
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|     // in the implementation file
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|     IMPLMENT_VARIANT_OBJECT(MyClass)
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|     
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|     // in the user code
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|     wxVariant variant;
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|     MyClass value;
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|     variant << value;
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|     
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|     // or
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|     value << variant;
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| \end{verbatim}
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| 
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| For this to work, MyClass must derive from \helpref{wxObject}{wxobject}, implement
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| the \helpref{wxWidgets RTTI system}{runtimeclassoverview}
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| and support the assignment operator and equality operator for itself. Ideally, it
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| should also be reference counted to make copying operations cheap and fast. This
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| can be most easily implemented using the reference counting support offered by
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| \helpref{wxObject}{wxobject} itself. By default, wxWidgets already implements
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| the shift operator conversion for a few of its drawing related classes:
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| 
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| \begin{verbatim}
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| IMPLEMENT_VARIANT_OBJECT(wxColour)
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| IMPLEMENT_VARIANT_OBJECT(wxImage)
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| IMPLEMENT_VARIANT_OBJECT(wxIcon)
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| IMPLEMENT_VARIANT_OBJECT(wxBitmap)
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| \end{verbatim}
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| 
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| \wxheading{Derived from}
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| 
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| \helpref{wxObject}{wxobject}
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| 
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| \wxheading{Include files}
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| 
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| <wx/variant.h>
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| 
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| \wxheading{See also}
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| 
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| \helpref{wxVariantData}{wxvariantdata}
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| 
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| \latexignore{\rtfignore{\wxheading{Members}}}
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| 
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| \membersection{wxVariant::wxVariant}\label{wxvariantctor}
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| 
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| \func{}{wxVariant}{\void}
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| 
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| Default constructor.
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| 
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| \func{}{wxVariant}{\param{const wxVariant\& }{variant}}
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| 
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| Copy constructor, uses \helpref{reference counting}{trefcount}.
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| 
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| \func{}{wxVariant}{\param{const wxChar*}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| \func{}{wxVariant}{\param{const wxString\&}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a string value.
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| 
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| \func{}{wxVariant}{\param{wxChar}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a character value.
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| 
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| \func{}{wxVariant}{\param{long}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from an integer value. You may need to cast to (long) to
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| avoid confusion with other constructors (such as the bool constructor).
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| 
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| \func{}{wxVariant}{\param{bool}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a boolean value.
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| 
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| \func{}{wxVariant}{\param{double}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a double-precision floating point value.
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| 
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| \func{}{wxVariant}{\param{const wxList\&}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a list of wxVariant objects. This constructor
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| copies {\it value}, the application is still responsible for
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| deleting {\it value} and its contents.
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| 
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| \func{}{wxVariant}{\param{void*}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a void pointer.
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| 
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| \func{}{wxVariant}{\param{wxObject*}{ value}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a wxObject pointer.
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| 
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| \func{}{wxVariant}{\param{wxVariantData*}{ data}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from user-defined data.  The variant holds onto the {\it data} pointer.
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| 
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| \func{}{wxVariant}{\param{wxDateTime\&}{ val}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a \helpref{wxDateTime}{wxdatetime}.
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| 
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| \func{}{wxVariant}{\param{wxArrayString\&}{ val}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from an array of strings.  This constructor copies {\it value} and its contents.
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| 
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| \func{}{wxVariant}{\param{DATE\_STRUCT*}{ val}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a odbc date value.  Represented internally by a \helpref{wxDateTime}{wxdatetime} value.
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| 
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| \func{}{wxVariant}{\param{TIME\_STRUCT*}{ val}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a odbc time value.  Represented internally by a \helpref{wxDateTime}{wxdatetime} value.
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| 
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| \func{}{wxVariant}{\param{TIMESTAMP\_STRUCT*}{ val}, \param{const wxString\& }{name = ``"}}
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| 
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| Construction from a odbc timestamp value.  Represented internally by a \helpref{wxDateTime}{wxdatetime} value.
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| 
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| \membersection{wxVariant::\destruct{wxVariant}}\label{wxvariantdtor}
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| 
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| \func{}{\destruct{wxVariant}}{\void}
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| 
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| Destructor.
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| 
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| Note that destructor is protected, so wxVariantData cannot usually
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| be deleted. Instead, \helpref{DecRef}{wxvariantdatadecref} should be called.
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| See \helpref{reference-counted object destruction}{refcountdestruct} for more info.
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| 
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| 
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| \membersection{wxVariant::Append}\label{wxvariantappend}
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| 
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| \func{void}{Append}{\param{const wxVariant\&}{ value}}
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| 
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| Appends a value to the list.
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| 
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| \membersection{wxVariant::Clear}\label{wxvariantclear}
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| 
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| \func{void}{Clear}{\void}
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| 
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| Makes the variant null by deleting the internal data and
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| set the name to {\it wxEmptyString}.
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| 
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| \membersection{wxVariant::ClearList}\label{wxvariantclearlist}
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| 
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| \func{void}{ClearList}{\void}
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| 
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| Deletes the contents of the list.
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| 
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| 
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| \membersection{wxVariant::Convert}\label{wxvariantconvert}
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| 
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| \constfunc{bool}{Convert}{\param{long*}{ value}}
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| 
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| \constfunc{bool}{Convert}{\param{bool*}{ value}}
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| 
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| \constfunc{bool}{Convert}{\param{double*}{ value}}
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| 
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| \constfunc{bool}{Convert}{\param{wxString*}{ value}}
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| 
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| \constfunc{bool}{Convert}{\param{wxChar*}{ value}}
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| 
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| \constfunc{bool}{Convert}{\param{wxDateTime*}{ value}}
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| 
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| Retrieves and converts the value of this variant to the type that {\it value} is.
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| 
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| 
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| \membersection{wxVariant::GetCount}\label{wxvariantgetcount}
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| 
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| \constfunc{size\_t}{GetCount}{\void}
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| 
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| Returns the number of elements in the list.
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| 
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| \membersection{wxVariant::Delete}\label{wxvariantdelete}
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| 
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| \func{bool}{Delete}{\param{size\_t }{item}}
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| 
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| Deletes the zero-based {\it item} from the list.
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| 
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| \membersection{wxVariant::GetArrayString}\label{wxvariantgetarraystring}
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| 
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| \constfunc{wxArrayString}{GetArrayString}{\void}
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| 
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| Returns the string array value.
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| 
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| \membersection{wxVariant::GetBool}\label{wxvariantgetbool}
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| 
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| \constfunc{bool}{GetBool}{\void}
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| 
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| Returns the boolean value.
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| 
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| \membersection{wxVariant::GetChar}\label{wxvariantgetchar}
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| 
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| \constfunc{wxChar}{GetChar}{\void}
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| 
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| Returns the character value.
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| 
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| \membersection{wxVariant::GetData}\label{wxvariantgetdata}
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| 
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| \constfunc{wxVariantData*}{GetData}{\void}
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| 
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| Returns a pointer to the internal variant data. To take ownership
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| of this data, you must call its \helpref{IncRef}{wxvariantdataincref}
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| method. When you stop using it, \helpref{DecRef}{wxvariantdatadecref}
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| must be likewise called.
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| 
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| \membersection{wxVariant::GetDateTime}\label{wxvariantgetdatetime}
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| 
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| \constfunc{wxDateTime}{GetDateTime}{\void}
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| 
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| Returns the date value.
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| 
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| \membersection{wxVariant::GetDouble}\label{wxvariantgetdouble}
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| 
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| \constfunc{double}{GetDouble}{\void}
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| 
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| Returns the floating point value.
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| 
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| \membersection{wxVariant::GetLong}\label{wxvariantgetlong}
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| 
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| \constfunc{long}{GetLong}{\void}
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| 
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| Returns the integer value.
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| 
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| \membersection{wxVariant::GetName}\label{wxvariantgetname}
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| 
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| \constfunc{const wxString\&}{GetName}{\void}
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| 
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| Returns a constant reference to the variant name.
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| 
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| \membersection{wxVariant::GetString}\label{wxvariantgetstring}
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| 
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| \constfunc{wxString}{GetString}{\void}
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| 
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| Gets the string value.
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| 
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| \membersection{wxVariant::GetType}\label{wxvariantgettype}
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| 
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| \constfunc{wxString}{GetType}{\void}
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| 
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| Returns the value type as a string. The built-in types are: bool, char, date, double, list, long, string, stringlist, time, void*.
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| 
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| If the variant is null, the value type returned is the string ``null" (not the empty string).
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| 
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| \membersection{wxVariant::GetVoidPtr}\label{wxvariantgetvoidptr}
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| 
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| \constfunc{void*}{GetVoidPtr}{\void}
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| 
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| Gets the void pointer value.
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| 
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| \membersection{wxVariant::GetWxObjectPtr}\label{wxvariantgetwxobjectptr}
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| 
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| \constfunc{wxObject*}{GetWxObjectPtr}{\void}
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| 
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| Gets the wxObject pointer value.
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| 
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| \membersection{wxVariant::Insert}\label{wxvariantinsert}
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| 
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| \func{void}{Insert}{\param{const wxVariant\&}{ value}}
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| 
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| Inserts a value at the front of the list.
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| 
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| \membersection{wxVariant::IsNull}\label{wxvariantisnull}
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| 
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| \constfunc{bool}{IsNull}{\void}
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| 
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| Returns true if there is no data associated with this variant, false if there is data.
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| 
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| \membersection{wxVariant::IsType}\label{wxvariantistype}
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| 
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| \constfunc{bool}{IsType}{\param{const wxString\&}{ type}}
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| 
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| Returns true if {\it type} matches the type of the variant, false otherwise.
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| 
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| \membersection{wxVariant::IsValueKindOf}\label{wxvariantisvaluekindof}
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| 
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| \constfunc{bool}{IsValueKindOf}{\param{const wxClassInfo* type}{ type}}
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| 
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| Returns true if the data is derived from the class described by {\it type}, false otherwise.
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| 
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| \membersection{wxVariant::MakeNull}\label{wxvariantmakenull}
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| 
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| \func{void}{MakeNull}{\void}
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| 
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| Makes the variant null by deleting the internal data.
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| 
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| \membersection{wxVariant::MakeString}\label{wxvariantmakestring}
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| 
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| \constfunc{wxString}{MakeString}{\void}
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| 
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| Makes a string representation of the variant value (for any type).
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| 
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| \membersection{wxVariant::Member}\label{wxvariantmember}
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| 
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| \constfunc{bool}{Member}{\param{const wxVariant\&}{ value}}
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| 
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| Returns true if {\it value} matches an element in the list.
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| 
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| \membersection{wxVariant::NullList}\label{wxvariantnulllist}
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| 
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| \func{void}{NullList}{\void}
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| 
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| Makes an empty list. This differs from a null variant which has no data; a null list
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| is of type list, but the number of elements in the list is zero.
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| 
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| \membersection{wxVariant::SetData}\label{wxvariantsetdata}
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| 
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| \func{void}{SetData}{\param{wxVariantData*}{ data}}
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| 
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| Sets the internal variant data, deleting the existing data if there is any.
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| 
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| \membersection{wxVariant::operator $=$}\label{wxvariantassignment}
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| 
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| \func{void}{operator $=$}{\param{const wxVariant\& }{value}}
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| 
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| \func{void}{operator $=$}{\param{wxVariantData* }{value}}
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| 
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| \func{void}{operator $=$}{\param{const wxString\& }{value}}
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| 
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| \func{void}{operator $=$}{\param{const wxChar* }{value}}
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| 
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| \func{void}{operator $=$}{\param{wxChar }{value}}
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| 
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| \func{void}{operator $=$}{\param{const long }{value}}
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| 
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| \func{void}{operator $=$}{\param{const bool }{value}}
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| 
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| \func{void}{operator $=$}{\param{const double }{value}}
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| 
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| \func{void}{operator $=$}{\param{void* }{value}}
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| 
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| \func{void}{operator $=$}{\param{wxObject* }{value}}
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| 
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| \func{void}{operator $=$}{\param{const wxList\& }{value}}
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| 
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| \func{void}{operator $=$}{\param{const wxDateTime\& }{value}}
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| 
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| \func{void}{operator $=$}{\param{const wxArrayString\& }{value}}
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| 
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| \func{void}{operator $=$}{\param{const DATE\_STRUCT* }{value}}
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| 
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| \func{void}{operator $=$}{\param{const TIME\_STRUCT* }{value}}
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| 
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| \func{void}{operator $=$}{\param{const TIMESTAMP\_STRUCT* }{value}}
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| 
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| Assignment operators, using \helpref{reference counting}{trefcount} when possible.
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| 
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| \membersection{wxVariant::operator $==$}\label{wxvarianteq}
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| 
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| \constfunc{bool}{operator $==$}{\param{const wxVariant\& }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{const wxString\& }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{const wxChar* }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{wxChar }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{const long }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{const bool }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{const double }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{void* }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{wxObject* }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{const wxList\& }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{const wxArrayString\& }{value}}
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| 
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| \constfunc{bool}{operator $==$}{\param{const wxDateTime\& }{value}}
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| 
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| Equality test operators.
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| 
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| \membersection{wxVariant::operator $!=$}\label{wxvariantneq}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const wxVariant\& }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const wxString\& }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const wxChar* }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{wxChar }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const long }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const bool }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const double }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{void* }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{wxObject* }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const wxList\& }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const wxArrayString\& }{value}}
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| 
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| \constfunc{bool}{operator $!=$}{\param{const wxDateTime\& }{value}}
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| 
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| Inequality test operators.
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| 
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| \membersection{wxVariant::operator $[]$}\label{wxvariantarray}
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| 
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| \constfunc{wxVariant}{operator $[]$}{\param{size\_t }{idx}}
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| 
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| Returns the value at {\it idx} (zero-based).
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| 
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| \func{wxVariant\&}{operator $[]$}{\param{size\_t }{idx}}
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| 
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| Returns a reference to the value at {\it idx} (zero-based). This can be used
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| to change the value at this index.
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| 
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| \membersection{wxVariant::operator wxChar}\label{wxvariantchar}
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| 
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| \constfunc{char}{operator wxChar}{\void}
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| 
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| Operator for implicit conversion to a wxChar, using \helpref{wxVariant::GetChar}{wxvariantgetchar}.
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| 
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| \membersection{wxVariant::operator double}\label{wxvariantdouble}
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| 
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| \constfunc{double}{operator double}{\void}
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| 
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| Operator for implicit conversion to a double, using \helpref{wxVariant::GetDouble}{wxvariantgetdouble}.
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| 
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| \constfunc{long}{operator long}{\void}
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| 
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| Operator for implicit conversion to a long, using \helpref{wxVariant::GetLong}{wxvariantgetlong}.
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| 
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| \membersection{wxVariant::operator wxString}\label{wxvariantwxstring}
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| 
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| \constfunc{wxString}{operator wxString}{\void}
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| 
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| Operator for implicit conversion to a string, using \helpref{wxVariant::MakeString}{wxvariantmakestring}.
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| 
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| \membersection{wxVariant::operator void*}\label{wxvariantvoid}
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| 
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| \constfunc{void*}{operator void*}{\void}
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| 
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| Operator for implicit conversion to a pointer to a void, using \helpref{wxVariant::GetVoidPtr}{wxvariantgetvoidptr}.
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| 
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| \membersection{wxVariant::operator wxDateTime}\label{wxvariantdatetime}
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| 
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| \constfunc{void*}{operator wxDateTime}{\void}
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| 
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| Operator for implicit conversion to a pointer to a \helpref{wxDateTime}{wxdatetime}, using \helpref{wxVariant::GetDateTime}{wxvariantgetdatetime}.
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| 
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| 
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| 
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| %% wxVariantData
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| 
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| 
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| \section{\class{wxVariantData}}\label{wxvariantdata}
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| 
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| The {\bf wxVariantData} class is used to implement a new type for \helpref{wxVariant}{wxvariant}. 
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| Derive from wxVariantData, and override the pure virtual functions.
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| 
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| wxVariantData is \helpref{reference counted}{refcount}, but you don't normally have to care about this, 
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| as wxVariant manages the count automatically. However, in case your application needs to take
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| ownership of wxVariantData, be aware that the object is created with reference count of 1,
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| and passing it to wxVariant will not increase this. In other words, \helpref{IncRef}{wxvariantdataincref}
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| needs to be called only if you both take ownership of wxVariantData and pass it to a wxVariant.
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| Also note that the destructor is protected, so you can never explicitly delete a wxVariantData
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| instance. Instead, \helpref{DecRef}{wxvariantdatadecref} will delete the object automatically
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| when the reference count reaches zero.
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| 
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| \wxheading{Derived from}
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| 
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| \helpref{wxObject}{wxobject}
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| 
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| \wxheading{Include files}
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| 
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| <wx/variant.h>
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| 
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| \wxheading{See also}
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| 
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| \helpref{wxVariant}{wxvariant}
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| 
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| \latexignore{\rtfignore{\wxheading{Members}}}
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| 
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| \membersection{wxVariantData::wxVariantData}\label{wxvariantdatactor}
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| 
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| \func{}{wxVariantData}{\void}
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| Default constructor.
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| 
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| \membersection{wxVariantData::DecRef}\label{wxvariantdatadecref}
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| \func{void}{DecRef}{\void}
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| 
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| Decreases reference count. If the count reaches zero, the object is
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| automatically deleted.
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| 
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| Note that destructor of wxVariantData is protected, so delete
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| cannot be used as normal. Instead, \helpref{DecRef}{wxvariantdatadecref} should be called.
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| 
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| 
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| \membersection{wxVariantData::Eq}\label{wxvariantdataeq}
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| \constfunc{bool}{Eq}{\param{wxVariantData\&}{ data}}
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| Returns true if this object is equal to {\it data}.
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| 
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| \membersection{wxVariantData::GetType}\label{wxvariantdatagettype}
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| 
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| \constfunc{wxString}{GetType}{\void}
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| Returns the string type of the data.
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| 
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| \membersection{wxVariantData::GetValueClassInfo}\label{wxvariantdatagetvalueclassinfo}
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| 
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| \constfunc{wxClassInfo*}{GetValueClassInfo}{\void}
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| If the data is a wxObject returns a pointer to the objects wxClassInfo structure, if
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| the data isn't a wxObject the method returns NULL.
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| 
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| \membersection{wxVariantData::IncRef}\label{wxvariantdataincref}
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| 
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| \func{void}{IncRef}{\void}
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| Increases reference count. Note that initially wxVariantData has reference count of 1.
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| 
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| \membersection{wxVariantData::Read}\label{wxvariantdataread}
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| \func{bool}{Read}{\param{ostream\&}{ stream}}
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| \func{bool}{Read}{\param{wxString\&}{ string}}
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| Reads the data from {\it stream} or {\it string}.
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| 
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| \membersection{wxVariantData::Write}\label{wxvariantdatawrite}
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| \constfunc{bool}{Write}{\param{ostream\&}{ stream}}
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| \constfunc{bool}{Write}{\param{wxString\&}{ string}}
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| Writes the data to {\it stream} or {\it string}.
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| 
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| 
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| \membersection{wxGetVariantCast}\label{wxgetvariantcast}
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| 
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| \func{classname *}{wxGetVariantCast}{wxVariant\&, classname}
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| 
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| This macro returns the data stored in {\it variant} cast to the type {\it classname *} if
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| the data is of this type (the check is done during the run-time) or
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| {\tt NULL} otherwise.
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| 
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| 
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| \wxheading{See also}
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| 
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| \helpref{RTTI overview}{runtimeclassoverview}\\
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| \helpref{wxDynamicCast}{wxdynamiccast}
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| 
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