Use lockable_adapter with const objects or const members

[anonymous]

I would like to use lockable_adapter pattern with const objects. Usually, we need to access in protected mode to one const object (read some value).

We have a compiler error when we connect unique_lock and one derived class from lockable_adapter and the object is const.

int func(const Class1& obj)
{
    boost::unique_lock<Class1> lock(obj);
    //boost::unique_lock<Class1> lock(const_cast<Class1&>(obj));
    return obj.get();
}

->

error C2664: 'boost::unique_lock<Mutex>::unique_lock(boost::upgrade_lock<Mutex> &)' : no se puede convertir el parámetro 1 de 'const Class1' a 'boost::upgrade_lock<Mutex> &'

The solution for us is rewrite the sentence with one const_cast<Class1> -> boost::unique_lock<Class1> lock(const_cast<Class1&>(obj));

We are using Visual C++ 2010

Best regards

[anonymous]

Error example