Mutex scoped_lock compile errors

From: Darren Vincent Hart (dvhart_at_[hidden])
Date: 2003-06-09 19:25:33

Esteemed Boost Gurus,

I am trying to compile a method with a scoped_lock call.  If I use a
mutex object declared in the class implementation file (logger.cpp) it
builds, if I use a mutex of the same type declared as a private member
of the logger class (in logger.h), I get the following compiler error:

logger.cpp: In member function `void pel::logger::info(const
std::string&,
   const std::string&, int, const std::string&) const':
logger.cpp:36: error: no matching function for call to `
   boost::detail::thread::scoped_lock<boost::mutex>::scoped_lock(const
   boost::mutex&)'
/usr/include/boost/thread/detail/lock.hpp:62: error: candidates are:
   boost::detail::thread::scoped_lock<boost::mutex>::scoped_lock(const
   boost::detail::thread::scoped_lock<boost::mutex>&)
/usr/include/boost/thread/detail/lock.hpp:67: error:
   boost::detail::thread::scoped_lock<Mutex>::scoped_lock(Mutex&, bool =
true)
   [with Mutex = boost::mutex]
make: *** [logger.o] Error 1

The relevant method from the implementation file is as follows:

void logger::info(const std::string& msg, const std::string& file, int
line, const std::string& function) const
{ 
  // io_mutex is declared above in the pel namespace
  boost::mutex::scoped_lock scoped_lock(io_mutex);  // no problem
  // mutex is a private member of the logger class
  boost::mutex::scoped_lock scoped_lock2(mutex);    // line 36, fails
  std::cout << "...blah..." << std::endl;
}

Can someone explain why these are treated differently by the compiler ?

Thanks,

Darren Hart
dvhart_at_[hidden]