Re: object copy with reference

From:
Werner <werasm@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Mon, 26 Sep 2011 01:26:23 -0700 (PDT)
Message-ID:
<96579252-6676-42c5-ae77-a09ef2a31e91@i28g2000yqn.googlegroups.com>
On Sep 25, 1:43 pm, Philipp Kraus <philipp.kr...@flashpixx.de> wrote:

Hello,

I need a tip / hint for solving the following problem:

I have a class method that is run in different threads:
myclass::mythreadmethod( mysuperclass& )

mysuperclass is a reference variable, that is used during the thread is
running.
Anyway the method should be myclass::mythreadmethod( mysuperclass ), so t=

hat

each running thread has a own local copy of the object, but I can't
switch the parameter
because the method is derivated of another class.

I need in the method a local (deep-copy) of my object. So I create a
clone method like
myclass::mythreadmethod( mysuperclass& pobj )
{
    mysuperclass& lobj = p_obj.clone();

}

In this case I get the compiler error, that I try to set up a temporary
assignment.

The try to do it like
myclass::mythreadmethod( mysuperclass& pobj )
{
    mysuperclass& lobj;
   p_obj.clone(lobj);}

create the message l_obj isn't initializate.

Does anyone has some tips to create a working solution? The perfect solut=

ion

should be a deep-copy of the pobj reference

Thanks

Phil


How about making mysuperclass a pointer (or a smart pointer of some
kind), then you can initialize it to zero (or in the case of smart_ptr
it happens automatically). I'd use scoped_ptr in this case..., but as
example I'd this use a bald pointer...

struct MySuper
{
  virtual MySuper* clone() const = 0;

  //... rest of interface

  //... lets not forget this...
  virtual ~MySuper() = 0;
};

class Thread
{
  public:
    Thread();
    ~Thread();
    void associate( MySuper& super );

  private:
    MySuper* super_;
};

//x.cpp
void Thread::associate( MySuper& super )
{
  super_ = super.clone();
}

Thread::Thread()
: super_() //Don't forget this for bald pointers...
{ }

Thread::~Thread()
{
  delete super_;
}

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