Re: Comment on my adapter concept

Le Chaud Lapin <>
Thu, 3 Jul 2008 03:28:04 CST
On Jul 2, 12:10 pm, Oncaphillis <> wrote:

I'm working on an adapter for a C plugin API.

Why? What is it good for? :)

  Well it irons your shirts, feeds your kids, walks the
dog and pays the mortgage :-)

  It's just a C-Style plugin system where each time a new
plugin is meant to be written a couple of function pointers
have to be initialized to NULL or a valid function pointer.
The whole code is very C++-stylish already. They have
structs mimicking a std::string and things that look
like a streambuf. So I'm covering this all under a

So e.g. something like

int_plugin(*p) {
   p->alloc = my_alloc;
   p->free = my_free;

   p->do_foo1 = NULL;
   p->do_foo2 = my_do_foo2;



int_plugin<M>(*p) {
   p->alloc = module_adapter<M>::alloc;
   p->free = module_adapter<M>::free;
   p->do_foo1 = module_adapter<M>::do_foo1;


Notice that the second function is module independent
"do_foo1" will become NULL whenever the module class
doesn't declare a do_foo1 method. Whereas the first
approach has to be rewritten whenever the module interface
changes. This goes down to the module_traits<M>::has_function::do_xyz
enum. In my example code these values are set explicitly, but
I already check via SFINAE if the corresponding method exists.

Hope that explains why

First, you should know, it took me a while to figure out the context,
meaning, it might help, while describing your facility, that you
specify an overall architecture. It is not clear [to me at least]
whether the plug-in thing was written in C++, and the other thing was C
++, or vice-versa. Maybe a one-line diagram showing the executable
pieces in Windows or Linux:

[executable thing]---[executable thing]

Which of these ^^^^ is the plug-in, and which language are these
things written in?

Also, but asking what is this good for...yes, we all know the syntax
of C++ and that amusing tricks can be done with templates and
pointers. :) But surely you have a motivation beyond that! How about
a real example? That's what I meant when asking what it is good for.

Just curious,

-Le Chaud Lapin-

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