Re: [Boost-users] c2248 with a queue!

Subject: Re: [Boost-users] c2248 with a queue!
From: Adam Romanek (a.romanek_at_[hidden])
Date: 2011-07-20 03:43:56

Ok, I analyzed your problem once again.

It seems you're trying to make a copy of 'concurrent_queue<Data>' 
somewhere in your code:

--
This diagnostic occurred in the compiler generated function
 > 'concurrent_queue<Data>::concurrent_queue(concurrent_queue<Data> &)')
--
you can see the copy constructor called. the problem is that 
boost::mutex and boost::condition_variable are instances of 
boost::noncopyable (copy constructor and assignment operator are private 
to prevent from copying objects).
you have two options:
1) prevent copying 'concurrent_queue' objects
2) implement copy constructor in 'concurrent_queue' to initialize 
'the_mutex' and 'the_condition_variable' using their default constructors
WBR,
Adam Romanek
On 07/20/2011 09:21 AM, Sean Farrow wrote:
> Hi:
>
> I’m using a queue written I think as I remember by Antony Williams
> (sorry if this is incorrect but it was certainly someone in the uk).
>
> The code is below, I’m getting 2 c2248 errors indicated by visual c++
> 2010 at the last line of the class i.e the line with };
>
> Does anyone know what’s causing this?
>
> The errors are:
>
> 1>d:\dropbox\mackie display reader\surface reader\surface
> reader\queue.hpp(18): error C2248: 'boost::mutex::mutex' : cannot access
> private member declared in class 'boost::mutex'
>
> c:\program files\boost\boost\thread\win32\mutex.hpp(26) : see
> declaration of 'boost::mutex::mutex'
>
> c:\program files\boost\boost\thread\win32\mutex.hpp(22) : see
> declaration of 'boost::mutex'
>
> This diagnostic occurred in the compiler generated function
> 'concurrent_queue<Data>::concurrent_queue(concurrent_queue<Data> &)'
>
> with
>
> [
>
> Data=PmEvent
>
> ]
>
> 1>d:\dropbox\mackie display reader\surface reader\surface
> reader\queue.hpp(18): error C2248:
> 'boost::condition_variable::condition_variable' : cannot access private
> member declared in class 'boost::condition_variable'
>
> c:\program files\boost\boost\thread\win32\condition_variable.hpp(299) :
> see declaration of 'boost::condition_variable::condition_variable'
>
> c:\program files\boost\boost\thread\win32\condition_variable.hpp(295) :
> see declaration of 'boost::condition_variable'
>
> This diagnostic occurred in the compiler generated function
> 'concurrent_queue<Data>::concurrent_queue(concurrent_queue<Data> &)'
>
> with
>
> [
>
> Data=PmEvent
>
> ]
>
> PmEvent is just a standard c structure:
>
> typedefstruct {
>
> PmMessage message;
>
> PmTimestamp timestamp;
>
> } PmEvent;
>
> PmTimestamp and PmMessage are defined as:
>
> typedefint32_t PmMessage/PmTimeStamp;
>
> any help appreciated.
>
> Cheers
>
> Sean.
>
> --begin code—
>
> #include<queue>
>
> #include<boost/thread/mutex.hpp>
>
> #include<boost/thread/condition_variable.hpp>
>
> template<typename Data>
>
> classconcurrent_queue {
>
> private:
>
> boost::mutex the_mutex;
>
> boost::condition_variable the_condition_variable;
>
> std::queue<Data> the_data;
>
> public:
>
> void push(Data const& data)
>
> {
>
> boost::mutex::scoped_lock lock(the_mutex);
>
> the_queue.push(data);
>
> lock.unlock();
>
> the_condition_variable.notify_one();
>
> }
>
> };
>
> --end code--
>
>
>
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