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Copyright Douglas Gregor 2001-2004
Copyright Frank Mori Hess 2007-2009

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<section last-revision="$Date: 2007-06-12 14:01:23 -0400 (Tue, 12 Jun 2007) $">
  <title>Introduction</title>

  <para>The Boost.Signals2 library is an implementation of a managed
  signals and slots system. Signals represent callbacks with multiple
  targets, and are also called publishers or events in similar
  systems. Signals are connected to some set of slots, which are
  callback receivers (also called event targets or subscribers), which
  are called when the signal is "emitted."</para>

  <para>Signals and slots are managed, in that signals and slots (or,
  more properly, objects that occur as part of the slots) can track
  connections and are capable of automatically disconnecting signal/slot
  connections when either is destroyed. This enables the user to make
  signal/slot connections without expending a great effort to manage the
  lifetimes of those connections with regard to the lifetimes of all
  objects involved.</para>

  <para>When signals are connected to multiple slots, there is a
  question regarding the relationship between the return values of the
  slots and the return value of the signals. Boost.Signals2 allows the
  user to specify the manner in which multiple return values are
  combined.</para>

  <section>
    <title>Signals2</title>
    <para>This documentation describes a thread-safe variant of the
    original Boost.Signals library.  There have been some changes to
    the interface to support thread-safety, mostly with respect to
    automatic connection management.  This implementation was written by
    Frank Mori Hess.  Acknowledgements are also due to Timmo Stange, Peter
    Dimov, and Gottlob Frege for ideas and feedback, and to Douglas Gregor
    for the original version of Boost.Signals this effort was based on.
    </para>
  </section>
</section>