Re: [PATCH] Add DISABLE_COPY_AND_ASSIGN

[Pedro Alves <palves@redhat.com>]

On 07/18/2017 04:13 PM, Yao Qi wrote:
> Pedro Alves <palves@redhat.com> writes:
> 
>> Yes, please.  I've been meaning to add something like this for a while.
>>
>> IMO, this could go in include/ansidecl.h, with a fallback version for
>> #if __cplusplus < C++11 that declares the methods without =delete (you
>> get a link error instead).
>>
> 
> I thought about adding this into include/, but can't find the right
> file.  I'll move the macro to include/ansidecl.h.

Thanks.  Note that that file is maintained by gcc.

> 
>>>  /* Pull in gdb::unique_xmalloc_ptr.  */
>>>  #include "common/gdb_unique_ptr.h"
>>>  
>>> +#define DISABLE_COPY_AND_ASSIGN(TYPE)		\
>>> +  TYPE (const TYPE&) = delete;			\
>>> +  void operator= (const TYPE &) = delete;
>>> +
>>
>> Should this have an intro comment?
>>
> 
> I thought it is too simple to have a comment :)  How about this?
> 
> /* A macro to disable the copy constructor and assignment operator.
>    When building with C++ 11, explicitly delete these methods.
>    Otherwise, place this macro in the private: declarations of a class.  */

How about this tweak:

 /* A macro to disable the copy constructor and assignment operator.
    When building with C++11 and above, the methods are explicitly
    deleted, causing a compile-time error if something tries to copy.
    For C++03, this just declares the methods, causing a link-time
    error if the methods end up called (assuming you don't
    define them).  For C++03, for best results, place the macro
    under the private: access specifier, so that most attempts at
    copy are caught at compile-time.  */

Thanks,
Pedro Alves