d2a48d5cbc
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@52857 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
485 lines
14 KiB
C++
485 lines
14 KiB
C++
///////////////////////////////////////////////////////////////////////////////
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// Name: wx/scopeguard.h
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// Purpose: declares wxwxScopeGuard and related macros
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// Author: Vadim Zeitlin
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// Modified by:
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// Created: 03.07.2003
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// RCS-ID: $Id$
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// Copyright: (c) 2003 Vadim Zeitlin <vadim@wxwidgets.org>
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// Licence: wxWindows licence
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///////////////////////////////////////////////////////////////////////////////
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/*
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Acknowledgements: this header is heavily based on (well, almost the exact
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copy of) ScopeGuard.h by Andrei Alexandrescu and Petru Marginean published
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in December 2000 issue of C/C++ Users Journal.
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http://www.cuj.com/documents/cujcexp1812alexandr/
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*/
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#ifndef _WX_SCOPEGUARD_H_
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#define _WX_SCOPEGUARD_H_
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#include "wx/defs.h"
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#include "wx/except.h"
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// ----------------------------------------------------------------------------
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// helpers
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// ----------------------------------------------------------------------------
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#ifdef __WATCOMC__
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// WATCOM-FIXME: C++ of Open Watcom 1.3 doesn't like OnScopeExit() created
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// through template so it must be workarounded with dedicated inlined macro.
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// For compatibility with Watcom compilers wxPrivate::OnScopeExit must be
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// replaced with wxPrivateOnScopeExit but in user code (for everyone who
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// doesn't care about OW compatibility) wxPrivate::OnScopeExit still works.
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#define wxPrivateOnScopeExit(guard) \
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{ \
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if ( !(guard).WasDismissed() ) \
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{ \
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wxTRY \
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{ \
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(guard).Execute(); \
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} \
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wxCATCH_ALL(;) \
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} \
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}
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#define wxPrivateUse(n) wxUnusedVar(n)
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#else
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// namespace support was first implemented in gcc-2.95,
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// so avoid using it for older versions.
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#if !defined(__GNUC__) || wxCHECK_GCC_VERSION(2, 95)
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#define wxHAS_NAMESPACES
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namespace wxPrivate
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{
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#else
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#define wxPrivate
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#endif
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// in the original implementation this was a member template function of
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// ScopeGuardImplBase but gcc 2.8 which is still used for OS/2 doesn't
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// support member templates and so we must make it global
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template <class ScopeGuardImpl>
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void OnScopeExit(ScopeGuardImpl& guard)
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{
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if ( !guard.WasDismissed() )
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{
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// we're called from ScopeGuardImpl dtor and so we must not throw
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wxTRY
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{
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guard.Execute();
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}
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wxCATCH_ALL(;) // do nothing, just eat the exception
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}
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}
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// just to avoid the warning about unused variables
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template <class T>
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void Use(const T& WXUNUSED(t))
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{
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}
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#if !defined(__GNUC__) || wxCHECK_GCC_VERSION(2, 95)
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} // namespace wxPrivate
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#endif
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#define wxPrivateOnScopeExit(n) wxPrivate::OnScopeExit(n)
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#define wxPrivateUse(n) wxPrivate::Use(n)
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#endif
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// ============================================================================
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// wxScopeGuard for functions and functors
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// ============================================================================
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// ----------------------------------------------------------------------------
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// wxScopeGuardImplBase: used by wxScopeGuardImpl[0..N] below
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// ----------------------------------------------------------------------------
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class wxScopeGuardImplBase
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{
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public:
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wxScopeGuardImplBase() : m_wasDismissed(false) { }
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wxScopeGuardImplBase(const wxScopeGuardImplBase& other)
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: m_wasDismissed(other.m_wasDismissed)
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{
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other.Dismiss();
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}
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void Dismiss() const { m_wasDismissed = true; }
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// for OnScopeExit() only (we can't make it friend, unfortunately)!
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bool WasDismissed() const { return m_wasDismissed; }
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protected:
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~wxScopeGuardImplBase() { }
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// must be mutable for copy ctor to work
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mutable bool m_wasDismissed;
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private:
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wxScopeGuardImplBase& operator=(const wxScopeGuardImplBase&);
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};
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// wxScopeGuard is just a reference, see the explanation in CUJ article
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typedef const wxScopeGuardImplBase& wxScopeGuard;
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// ----------------------------------------------------------------------------
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// wxScopeGuardImpl0: scope guard for actions without parameters
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// ----------------------------------------------------------------------------
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template <class F>
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class wxScopeGuardImpl0 : public wxScopeGuardImplBase
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{
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public:
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static wxScopeGuardImpl0<F> MakeGuard(F fun)
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{
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return wxScopeGuardImpl0<F>(fun);
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}
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~wxScopeGuardImpl0() { wxPrivateOnScopeExit(*this); }
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void Execute() { m_fun(); }
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protected:
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wxScopeGuardImpl0(F fun) : m_fun(fun) { }
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F m_fun;
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wxScopeGuardImpl0& operator=(const wxScopeGuardImpl0&);
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};
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template <class F>
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inline wxScopeGuardImpl0<F> wxMakeGuard(F fun)
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{
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return wxScopeGuardImpl0<F>::MakeGuard(fun);
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}
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// ----------------------------------------------------------------------------
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// wxScopeGuardImpl1: scope guard for actions with 1 parameter
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// ----------------------------------------------------------------------------
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template <class F, class P1>
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class wxScopeGuardImpl1 : public wxScopeGuardImplBase
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{
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public:
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static wxScopeGuardImpl1<F, P1> MakeGuard(F fun, P1 p1)
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{
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return wxScopeGuardImpl1<F, P1>(fun, p1);
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}
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~wxScopeGuardImpl1() { wxPrivateOnScopeExit(* this); }
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void Execute() { m_fun(m_p1); }
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protected:
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wxScopeGuardImpl1(F fun, P1 p1) : m_fun(fun), m_p1(p1) { }
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F m_fun;
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const P1 m_p1;
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wxScopeGuardImpl1& operator=(const wxScopeGuardImpl1&);
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};
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template <class F, class P1>
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inline wxScopeGuardImpl1<F, P1> wxMakeGuard(F fun, P1 p1)
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{
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return wxScopeGuardImpl1<F, P1>::MakeGuard(fun, p1);
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}
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// ----------------------------------------------------------------------------
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// wxScopeGuardImpl2: scope guard for actions with 2 parameters
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// ----------------------------------------------------------------------------
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template <class F, class P1, class P2>
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class wxScopeGuardImpl2 : public wxScopeGuardImplBase
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{
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public:
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static wxScopeGuardImpl2<F, P1, P2> MakeGuard(F fun, P1 p1, P2 p2)
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{
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return wxScopeGuardImpl2<F, P1, P2>(fun, p1, p2);
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}
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~wxScopeGuardImpl2() { wxPrivateOnScopeExit(*this); }
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void Execute() { m_fun(m_p1, m_p2); }
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protected:
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wxScopeGuardImpl2(F fun, P1 p1, P2 p2) : m_fun(fun), m_p1(p1), m_p2(p2) { }
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F m_fun;
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const P1 m_p1;
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const P2 m_p2;
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wxScopeGuardImpl2& operator=(const wxScopeGuardImpl2&);
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};
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template <class F, class P1, class P2>
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inline wxScopeGuardImpl2<F, P1, P2> wxMakeGuard(F fun, P1 p1, P2 p2)
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{
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return wxScopeGuardImpl2<F, P1, P2>::MakeGuard(fun, p1, p2);
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}
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// ============================================================================
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// wxScopeGuards for object methods
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// ============================================================================
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// ----------------------------------------------------------------------------
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// wxObjScopeGuardImpl0
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// ----------------------------------------------------------------------------
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template <class Obj, class MemFun>
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class wxObjScopeGuardImpl0 : public wxScopeGuardImplBase
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{
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public:
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static wxObjScopeGuardImpl0<Obj, MemFun>
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MakeObjGuard(Obj& obj, MemFun memFun)
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{
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return wxObjScopeGuardImpl0<Obj, MemFun>(obj, memFun);
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}
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~wxObjScopeGuardImpl0() { wxPrivateOnScopeExit(*this); }
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void Execute() { (m_obj.*m_memfun)(); }
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protected:
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wxObjScopeGuardImpl0(Obj& obj, MemFun memFun)
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: m_obj(obj), m_memfun(memFun) { }
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Obj& m_obj;
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MemFun m_memfun;
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};
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template <class Obj, class MemFun>
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inline wxObjScopeGuardImpl0<Obj, MemFun> wxMakeObjGuard(Obj& obj, MemFun memFun)
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{
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return wxObjScopeGuardImpl0<Obj, MemFun>::MakeObjGuard(obj, memFun);
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}
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template <class Obj, class MemFun, class P1>
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class wxObjScopeGuardImpl1 : public wxScopeGuardImplBase
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{
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public:
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static wxObjScopeGuardImpl1<Obj, MemFun, P1>
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MakeObjGuard(Obj& obj, MemFun memFun, P1 p1)
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{
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return wxObjScopeGuardImpl1<Obj, MemFun, P1>(obj, memFun, p1);
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}
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~wxObjScopeGuardImpl1() { wxPrivateOnScopeExit(*this); }
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void Execute() { (m_obj.*m_memfun)(m_p1); }
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protected:
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wxObjScopeGuardImpl1(Obj& obj, MemFun memFun, P1 p1)
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: m_obj(obj), m_memfun(memFun), m_p1(p1) { }
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Obj& m_obj;
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MemFun m_memfun;
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const P1 m_p1;
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};
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template <class Obj, class MemFun, class P1>
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inline wxObjScopeGuardImpl1<Obj, MemFun, P1>
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wxMakeObjGuard(Obj& obj, MemFun memFun, P1 p1)
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{
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return wxObjScopeGuardImpl1<Obj, MemFun, P1>::MakeObjGuard(obj, memFun, p1);
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}
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template <class Obj, class MemFun, class P1, class P2>
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class wxObjScopeGuardImpl2 : public wxScopeGuardImplBase
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{
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public:
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static wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>
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MakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2)
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{
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return wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>(obj, memFun, p1, p2);
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}
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~wxObjScopeGuardImpl2() { wxPrivateOnScopeExit(*this); }
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void Execute() { (m_obj.*m_memfun)(m_p1, m_p2); }
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protected:
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wxObjScopeGuardImpl2(Obj& obj, MemFun memFun, P1 p1, P2 p2)
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: m_obj(obj), m_memfun(memFun), m_p1(p1), m_p2(p2) { }
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Obj& m_obj;
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MemFun m_memfun;
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const P1 m_p1;
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const P2 m_p2;
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};
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template <class Obj, class MemFun, class P1, class P2>
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inline wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>
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wxMakeObjGuard(Obj& obj, MemFun memFun, P1 p1, P2 p2)
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{
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return wxObjScopeGuardImpl2<Obj, MemFun, P1, P2>::
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MakeObjGuard(obj, memFun, p1, p2);
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}
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// ----------------------------------------------------------------------------
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// wxVariableSetter: use the same technique as for wxScopeGuard to allow
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// setting a variable to some value on block exit
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// ----------------------------------------------------------------------------
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#ifdef wxHAS_NAMESPACES
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namespace wxPrivate
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{
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// empty class just to be able to define a reference to it
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class VariableSetterBase { };
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typedef const VariableSetterBase& VariableSetter;
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template <typename T, typename U>
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class VariableSetterImpl : public VariableSetterBase
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{
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public:
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VariableSetterImpl(T& var, const U& value)
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: m_var(var),
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m_value(value)
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{
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}
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~VariableSetterImpl()
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{
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m_var = m_value;
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}
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private:
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T& m_var;
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const U& m_value;
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// suppress the warning about assignment operator not being generated
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VariableSetterImpl<T, U>& operator=(const VariableSetterImpl<T, U>&);
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};
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template <typename T>
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class VariableNullerImpl : public VariableSetterBase
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{
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public:
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VariableNullerImpl(T& var)
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: m_var(var)
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{
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}
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~VariableNullerImpl()
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{
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m_var = NULL;
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}
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private:
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T& m_var;
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VariableNullerImpl<T>& operator=(const VariableNullerImpl<T>&);
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};
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} // namespace wxPrivate
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template <typename T, typename U>
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inline
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wxPrivate::VariableSetterImpl<T, U> wxMakeVarSetter(T& var, const U& value)
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{
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return wxPrivate::VariableSetterImpl<T, U>(var, value);
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}
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// calling wxMakeVarSetter(ptr, NULL) doesn't work because U is deduced to be
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// "int" and subsequent assignment of "U" to "T *" fails, so provide a special
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// function for this special case
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template <typename T>
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inline
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wxPrivate::VariableNullerImpl<T> wxMakeVarNuller(T& var)
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{
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return wxPrivate::VariableNullerImpl<T>(var);
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}
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#endif // wxHAS_NAMESPACES
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// ============================================================================
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// macros for declaring unnamed scoped guards (which can't be dismissed)
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// ============================================================================
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// NB: the original code has a single (and much nicer) ON_BLOCK_EXIT macro
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// but this results in compiler warnings about unused variables and I
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// didn't find a way to work around this other than by having different
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// macros with different names or using a less natural syntax for passing
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// the arguments (e.g. as Boost preprocessor sequences, which would mean
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// having to write wxON_BLOCK_EXIT(fwrite, (buf)(size)(n)(fp)) instead of
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// wxON_BLOCK_EXIT4(fwrite, buf, size, n, fp)).
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#define wxGuardName wxMAKE_UNIQUE_NAME(wxScopeGuard)
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#define wxON_BLOCK_EXIT0_IMPL(n, f) \
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wxScopeGuard n = wxMakeGuard(f); \
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wxPrivateUse(n)
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#define wxON_BLOCK_EXIT0(f) \
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wxON_BLOCK_EXIT0_IMPL(wxGuardName, f)
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#define wxON_BLOCK_EXIT_OBJ0_IMPL(n, o, m) \
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wxScopeGuard n = wxMakeObjGuard(o, m); \
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wxPrivateUse(n)
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#define wxON_BLOCK_EXIT_OBJ0(o, m) \
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wxON_BLOCK_EXIT_OBJ0_IMPL(wxGuardName, o, &m)
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#define wxON_BLOCK_EXIT_THIS0(m) \
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wxON_BLOCK_EXIT_OBJ0(*this, m)
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#define wxON_BLOCK_EXIT1_IMPL(n, f, p1) \
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wxScopeGuard n = wxMakeGuard(f, p1); \
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wxPrivateUse(n)
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#define wxON_BLOCK_EXIT1(f, p1) \
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wxON_BLOCK_EXIT1_IMPL(wxGuardName, f, p1)
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#define wxON_BLOCK_EXIT_OBJ1_IMPL(n, o, m, p1) \
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wxScopeGuard n = wxMakeObjGuard(o, m, p1); \
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wxPrivateUse(n)
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#define wxON_BLOCK_EXIT_OBJ1(o, m, p1) \
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wxON_BLOCK_EXIT_OBJ1_IMPL(wxGuardName, o, &m, p1)
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#define wxON_BLOCK_EXIT_THIS1(m, p1) \
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wxON_BLOCK_EXIT_OBJ1(*this, m, p1)
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#define wxON_BLOCK_EXIT2_IMPL(n, f, p1, p2) \
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wxScopeGuard n = wxMakeGuard(f, p1, p2); \
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wxPrivateUse(n)
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#define wxON_BLOCK_EXIT2(f, p1, p2) \
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wxON_BLOCK_EXIT2_IMPL(wxGuardName, f, p1, p2)
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#define wxON_BLOCK_EXIT_OBJ2_IMPL(n, o, m, p1, p2) \
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wxScopeGuard n = wxMakeObjGuard(o, m, p1, p2); \
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wxPrivateUse(n)
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#define wxON_BLOCK_EXIT_OBJ2(o, m, p1, p2) \
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wxON_BLOCK_EXIT_OBJ2_IMPL(wxGuardName, o, &m, p1, p2)
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#define wxON_BLOCK_EXIT_THIS2(m, p1, p2) \
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wxON_BLOCK_EXIT_OBJ2(*this, m, p1, p2)
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#define wxSetterName wxMAKE_UNIQUE_NAME(wxVarSetter)
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#define wxON_BLOCK_EXIT_SET_IMPL(n, var, value) \
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wxPrivate::VariableSetter n = wxMakeVarSetter(var, value); \
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wxPrivateUse(n)
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#define wxON_BLOCK_EXIT_SET(var, value) \
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wxON_BLOCK_EXIT_SET_IMPL(wxSetterName, var, value)
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#define wxON_BLOCK_EXIT_NULL_IMPL(n, var) \
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wxPrivate::VariableSetter n = wxMakeVarNuller(var); \
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wxPrivateUse(n)
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#define wxON_BLOCK_EXIT_NULL(ptr) \
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wxON_BLOCK_EXIT_NULL_IMPL(wxSetterName, ptr)
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#endif // _WX_SCOPEGUARD_H_
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