Re: [Boost-bugs] [Boost C++ Libraries] #10128: Use lockable_adapter with const objects or const members

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #10128: Use lockable_adapter with const objects or const members
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-06-17 16:14:31

#10128: Use lockable_adapter with const objects or const members
-------------------------------+----------------------
  Reporter:  anonymous         |      Owner:  viboes
      Type:  Feature Requests  |     Status:  assigned
 Milestone:  To Be Determined  |  Component:  thread
   Version:  Boost 1.54.0      |   Severity:  Problem
Resolution:                    |   Keywords:
-------------------------------+----------------------
Changes (by viboes):

 * owner:  anthonyw => viboes
 * status:  new => assigned


Old description:

> 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

New description:

 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

--
-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/10128#comment:1>
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