Re: [boost] Pimpl Again?

30 May 2016

      On 2016-05-30 14:18, Gavin Lambert wrote:
...
On 30/05/2016 15:16, Vladimir Batov wrote:
...
So, in your view, should we try and have pimpl in Boost? I think we
should as it'd be useful IMO...
As I said at the start, yes, I think this has potential usefulness and
it would be nice to get something like it into Boost.
Excellent.
...
...
As it's the template specialisation which causes most of my concern,
my main query is whether it's really necessary or if it could be
structured differently to avoid this instead.
...  Taking the Book example from the docs...
... we get something like this:
namespace library
{
    namespace detail
    {
        ...
    }
}
namespace boost
{
    template<> struct pimpllibrary::Book::implementation
    {
        implementation(string const& the_title,
                       string const& the_author)
            : title(the_title), author(the_author), price(0)
        {}
        ...
        bool check_isbn_10_digit() { ... }
        ...
        string  title;
        string author;
        int     price;
    };
}
namespace library
{
    Book::Book(string const& title, string const& author)
        : pimpl_type(title, author)
    {}
string const&
    Book::author() const
    {
        return (*this)->author;
    }
    ...
}
...
Yes, I understand. That's why I said before and still insist now that 
that's style... because I personally do not like

namespace library
{
     Book::Book(string const& title, string const& author)
         : pimpl_type(title, author)
     {}
}

as you move your code to the right and IMO just waste the space (you 
fill it with blanks instead of the code). So, I write

template<> struct boost::pimpllibrary::Book::implementation
{
     ....
}

library::Book::Book(string const& title, string const& author)
: pimpl_type(title, author)
{
      ...
}

Then, you might say you do not like fully qualified 
library::Book::Book(), etc... which in my view is, well, style... for me 
the "like" and "do not like" are usually the style triggers.