src/servers/registrar/Watcher.cpp

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  22 //      File Name:              Watcher.cpp
  23 //      Author:                 Ingo Weinhold (bonefish@users.sf.net)
  24 //      Description:    A Watcher represents a target of a watching service.
  25 //                                      A WatcherFilter represents a predicate on Watchers.
  26 //------------------------------------------------------------------------------
  27
  28 #include <Message.h>
  29
  30 #include "MessageDeliverer.h"
  31 #include "Watcher.h"
  32
  33 // Watcher
  34
  35 /*!     \class Watcher
  36         \brief A Watcher represents a target of a watching service.
  37
  38         The Watcher base class only has one attribute, a BMessenger which
  39         specifies the target to which notification messages shall be sent.
  40         SendMessage() actually sends the message to the target. It can be
  41         overridden in case of special needs.
  42 */
  43
  44 /*!     \var Watcher::fTarget
  45         \brief The watcher's message target.
  46 */
  47
  48 // constructor
  49 /*!     \brief Creates a new watcher with a specified target.
  50
  51         The supplied BMessenger is copied, that is the caller can delete the
  52         object when the constructor returns.
  53
  54         \param target The watcher's message target.
  55 */
  56 Watcher::Watcher(const BMessenger &target)
  57         : fTarget(target)
  58 {
  59 }
  60
  61 // destructor
  62 /*!     \brief Frees all resources associated with the object.
  63 */
  64 Watcher::~Watcher()
  65 {
  66 }
  67
  68 // Target
  69 /*!     \brief Returns the watcher's message target.
  70         \return The watcher's message target.
  71 */
  72 const BMessenger&
  73 Watcher::Target() const
  74 {
  75         return fTarget;
  76 }
  77
  78 // SendMessage
  79 /*!     \brief Sends the supplied message to the watcher's message target.
  80
  81         The method can be overridden by a derived class to e.g. add additional
  82         fields to the message. Note, that in this case the message must not be
  83         modified directly, but a copy has to be made.
  84
  85         \param message The message to be sent.
  86         \return \c B_OK, if everything went fine, another error code, if an error
  87                         occured.
  88 */
  89 status_t
  90 Watcher::SendMessage(BMessage *message)
  91 {
  92         return MessageDeliverer::Default()->DeliverMessage(message, fTarget);
  93 }
  94
  95
  96 // WatcherFilter
  97
  98 /*!     \class WatcherFilter
  99         \brief A WatcherFilter represents a predicate on Watchers.
 100
 101         It's only method Filter() returns whether a given Watcher and a BMessage
 102         satisfy the predicate. This class' Filter() implementation always returns
 103         \c true. Derived classes override it.
 104 */
 105
 106 // constructor
 107 /*!     \brief Creates a new WatchingFilter.
 108 */
 109 WatcherFilter::WatcherFilter()
 110 {
 111 }
 112
 113 // destructor
 114 /*!     \brief Frees all resources associated with the object.
 115 */
 116 WatcherFilter::~WatcherFilter()
 117 {
 118 }
 119
 120 // Filter
 121 /*!     \brief Returns whether the watcher-message pair satisfies the predicate
 122                    represented by this object.
 123
 124         Derived classes override this method. This version always returns \c true.
 125
 126         \param watcher The watcher in question.
 127         \param message The message in question.
 128         \return \c true.
 129 */
 130 bool
 131 WatcherFilter::Filter(Watcher *watcher, BMessage *message)
 132 {
 133         return true;
 134 }
 135