Re: [boost] Pimpl Again?

31 May 2016

      On Tue, May 31, 2016 at 3:15 PM, Vladimir Batov <
Vladimir.Batov@constrainttec.com> wrote:
...
On 2016-06-01 07:58, Emil Dotchevski wrote:
...
On Tue, May 31, 2016 at 2:48 PM, Rob Stewart  wrote:
...
The upside is not writing some calls one way and others the other way on
the same object, and having to remember which is which.
So, don't use the dot syntax. :)
Even I must say that from the "purist" point of view forcing free-function
API kinda violates the very basic OO paradigm -- the association between
data and behavior. From practical point of view it's "meh, big deal".
C++ provides alternative mechanisms to express that association, for
example:

namespace boost { template <class> class shared_ptr; };

namespace file
{
  struct handle;
  boost::shared_ptr<handle> open( char const * name );
  void read( handle *, void * buf, size_t size );
}

As a bonus, ADL allows unqualified calls to read (but, obviously, not to
open.)

That said, the most important feature of object-oriented design is data
encapsulation, which is actually stronger if types are left incomplete in
interfaces, compared to using private/protected.
...
Please do not get me wrong. I am not criticizing your approach. In fact,
to me it feels surprisingly potent just using the tools we've had
"forever". I feel that it is unlikely to "fly" with "general programming
population". :-)
Yes, I'm aware of that. It doesn't mean they have a point though. :)

I just can't support including yet another can of worms in the already
complicated name lookup/implicit instantiation/overload resolution process.
A compromise would be to allow the definition of non-friend members, like
this:

struct foo;
void foo::do_something();

This language change seems a lot safer than messing with the overload
resolution. Perhaps I'm wrong. Either way, I don't consider "but I want to
use the dot syntax" a very compelling argument.

Emil