Re: [Threads-devel] boost::condition and Lock concept

From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2007-11-27 09:09:59

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On Tuesday 27 November 2007 03:06 am, Anthony Williams wrote:
> > error: ‘class boost::unique_lock<boost::mutex>’ has no member named
> > ‘locked’
>
> Where does that error come from? The condition variable code doesn't use a
> locked() function, nor does unique_lock provide one.

I've attached a small program that generates the error when I try to compile 
it.  It's not actually related to conditions, all I have to do is try to use 
the locked() member of boost::mutex::scoped_lock (which is apparently a 
unique_lock).  Maybe the docs just haven't been updated (the Lock concept 
still says it requires a locked() member function, and a cast to const 
void*).

> The new trunk code provides two condition variable types:
> condition_variable and condition_variable_any.
>
> condition_variable works with unique_lock<mutex> ONLY, and the function
> signatures are explicit about that. condition_variable_any will work with
> anything that supports unlock() and lock().

Ah, good to hear.

- -- 
Frank
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        name="lock_compile_error.cpp"
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        filename="lock_compile_error.cpp"

#include <boost/thread/mutex.hpp>
#include <iostream>

int main()
{
        boost::mutex mut;
        boost::mutex::scoped_lock lock(mut);
        std::cout << "locked returns " << lock.locked() << std::endl;
        return 0;
}

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