On Apr 25, 12:53 pm, rwf_20 <rfr...@[EMAIL PROTECTED]
> wrote:
> I'd like to use pimpl to reduce dependencies as follows:
>
> // myClass.h
>
> #include <memory>
>
> class myClass {
> public:
> myClass();
>
> private:
> struct myStruct;
> std::auto_ptr<struct myStruct> m_pimpl;
>
> };
>
> // myClass.cpp
> #include "myClass.h"
>
> struct myClass::myStruct {
> // ...details
>
> };
>
> myClass::myClass() : m_pimpl(std::auto_ptr<myStruct>(new myStruct()))
> { }
>
> This compiles just fine, until I try to use myClass elsewhere. At
> this point, I get warnings like:
>
> "deletion of pointer to incomplete type 'myStruct'; no destructor
> called"
>
> I guess I understand why this happens, and it's fixed by declaring a
> destructor for myClass and defining it in the .cpp file. It just irks
> me that I need to define a blank destructor (the same thing the
> compiler should generate) to make this work. Googling this issue, I
> findhttp://www.gotw.ca/publications/using_auto_ptr_effectively.htm,
> in which Mr. Sutter demonstrates this same code and adds the comment:
>
> "In fact, if there's no other reason for explicitly writing a
> destructor, we don't need to bother with a custom destructor at all
> any more."
>
> I'm seeing that this is not the case. Unless (likely) I am doing
> something wrong. Thoughts?
>
> Thanks in advance,
>
> Ryan
>
> Is there a workaround for this issue? I know it's only a few more
> lines of code
I think you got it pretty much right. There are only two choices -
either have the full declaration for the pointed-to class available,
or provide an explicit destructor implementation for the containing
class.
Since the std::auto_ptr is a template, the (inline) synthesized
destructor for
your containing class would include inline code for destructing the
auto_ptr member, which in turn calls the pointed-to class destructor,
which is not available with only forward declaration.
--
Nikolai
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