[Dar-libdar_api] callback function context value

[Johnathan B. <jk...@us...>]

Hi Denis,

Apparently it is standard coding practice for API callback functions to=20
accept a "context value", which is a void *, that allows one to use a=20
class member function as a callback without resorting to a global pointer=20
variable.

As I understand dar, it uses a regular function as the callback. Could you=
=20
add perhaps a new set of callback setting functions to the libdar API that=
=20
accept a void * context value to be passed. It would be easy to keep=20
backwards compatibility with earlier libdar versions by redefining the=20
standard callback setting functions to call the new ones with NULL for the=
=20
void *.

There is a good tutorial at
http://www.function-pointer.org/callback.html
#3:  How to Implement Callbacks in C and C++

In the examples given, I currently use method B, but it would be better to=
=20
use method A to avoid using the global variable.

Cheers,
JB

=2D-=20
Johnathan K. Burchill, Ph.D.
jk...@us...