canvas/inc/base/disambiguationhelper.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
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   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
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  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20 #pragma once
  21
  22 #include <com/sun/star/lang/EventObject.hpp>
  23 #include <osl/mutex.hxx>
  24
  25
  26 /* Definition of the DisambiguationHelper class */
  27
  28 namespace canvas
  29 {
  30     /** Base class, initializing its own baseclass with m_aMutex.
  31
  32         This is necessary to make the CanvasBase, GraphicDeviceBase,
  33         etc. classes freely combinable - letting them perform this
  34         initialization would prohibit deriving e.g. CanvasBase from
  35         GraphicDeviceBase.
  36
  37         On top of that, disambiguates XEventListener::disposing and
  38         WeakComponentImplHelper::disposing.
  39
  40         Having two virtual methods with the same name, and not
  41         overriding them in every derived class, will hide one of
  42         them. Later trying to override the same method, will generate
  43         a new vtable slot, and lead to very hard to spot errors.
  44      */
  45     template< class Base > class DisambiguationHelper : public Base
  46     {
  47     protected:
  48         /** Construct DisambiguationHelper
  49
  50             This method is the whole purpose of this template:
  51             initializing a base class with the provided m_aMutex
  52             member (the WeakComponentImplHelper templates need that,
  53             as they require the lifetime of the mutex to extend
  54             theirs).
  55          */
  56         DisambiguationHelper() :
  57             Base( m_aMutex )
  58         {
  59         }
  60
  61         virtual void disposeThis()
  62         {}
  63         /// @throws css::uno::RuntimeException
  64         virtual void disposeEventSource( const css::lang::EventObject& )
  65         {}
  66
  67         mutable ::osl::Mutex m_aMutex;
  68
  69     private:
  70         virtual void SAL_CALL disposing() override
  71         { disposeThis(); }
  72
  73         virtual void SAL_CALL disposing( const css::lang::EventObject& Source ) override
  74         { disposeEventSource(Source); }
  75
  76     };
  77 }
  78
  79 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */