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Commit	Line	Data
	1	/////////////////////////////////////////////////////////////////////////////
	2	// Name: recguard.h
	3	// Purpose: interface of wxRecursionGuardFlag
	4	// Author: wxWidgets team
	5	// RCS-ID: $Id$
	6	// Licence: wxWindows licence
	7	/////////////////////////////////////////////////////////////////////////////
	8
	9	/**
	10	@class wxRecursionGuardFlag
	11
	12	This is a completely opaque class which exists only to be used with
	13	wxRecursionGuard, please see the example in that class' documentation.
	14
	15	@remarks
	16
	17	wxRecursionGuardFlag object must be declared @c static or the recursion
	18	would never be detected.
	19
	20	@library{wxbase}
	21	@category{misc}
	22	*/
	23	class wxRecursionGuardFlag
	24	{
	25	public:
	26
	27	};
	28
	29
	30
	31	/**
	32	@class wxRecursionGuard
	33
	34	wxRecursionGuard is a very simple class which can be used to prevent reentrancy
	35	problems in a function. It is not thread-safe and so should be used only in
	36	single-threaded programs or in combination with some thread synchronization
	37	mechanisms.
	38
	39	wxRecursionGuard is always used together with the
	40	wxRecursionGuardFlag like in this example:
	41
	42	@code
	43	void Foo()
	44	{
	45	static wxRecursionGuardFlag s_flag;
	46	wxRecursionGuard guard(s_flag);
	47	if ( guard.IsInside() )
	48	{
	49	// don't allow reentrancy
	50	return;
	51	}
	52
	53	...
	54	}
	55	@endcode
	56
	57	As you can see, wxRecursionGuard simply tests the flag value and sets it to
	58	@true if it hadn't been already set.
	59	IsInside() allows testing the old flag
	60	value. The advantage of using this class compared to directly manipulating the
	61	flag is that the flag is always reset in the wxRecursionGuard destructor and so
	62	you don't risk to forget to do it even if the function returns in an unexpected
	63	way (for example because an exception has been thrown).
	64
	65	@library{wxbase}
	66	@category{misc}
	67	*/
	68	class wxRecursionGuard
	69	{
	70	public:
	71	/**
	72	A wxRecursionGuard object must always be initialized with a @c static
	73	wxRecursionGuardFlag. The constructor saves the
	74	value of the flag to be able to return the correct value from
	75	IsInside().
	76	*/
	77	wxRecursionGuard(wxRecursionGuardFlag& flag);
	78
	79	/**
	80	The destructor resets the flag value so that the function can be entered again
	81	the next time.
	82
	83	@note This is not virtual, so this class is not meant to be derived
	84	from (besides, there is absolutely no reason to do it anyhow).
	85	*/
	86	~wxRecursionGuard();
	87
	88	/**
	89	Returns @true if we're already inside the code block "protected" by this
	90	wxRecursionGuard (i.e. between this line and the end of current scope).
	91	Usually the function using wxRecursionGuard takes some specific actions
	92	in such case (may be simply returning) to prevent reentrant calls to itself.
	93
	94	If this method returns @false, it is safe to continue.
	95	*/
	96	bool IsInside() const;
	97	};
	98