Re: [gtkmm] Passing a pointer to a class using D&D

["Timothy M. Shead" <tshead k-3d com>]

Miller, Ryan D wrote:

> Another question for the great readers of gtkmm list.  I need to access
> several fields of information from a class after a user performs a drag
> from that class onto another one.  (Both classes are derived from
> EventBoxes).  I figured out how to pass a single value, such as a
> string, based on the examples by casting the string into a guchar* and
> then using get_data_as_string on the receiving end.  In order to pass
> more than one thing, I was hoping to pass the address of the passing and
> then create a pointer to the passing class on the receiving end and use
> that to access what I need.  Is this a feasible way to do this?  In a
> more concise manner: I would like to pass a pointer to "this" using D&D.
> The code I have right now is below, but I end up with different values
> for the addresses on both ends.  Does anyone know how to do this?

Remember that in the general case, drag-and-drop can be between 
different processes, each with its own address-space.  As a consequence, 
you cannot pass-by-reference with dnd - it is implicitly making a copy 
of your data.  So depending on the complexity of your data, you could 
serialize it to a single delimited text string and use the UTF8 target, 
or use XML and UTF8, or you can create your own custom target and let 
dnd make a copy of your binary structure, but you will have to ensure 
that your binary structure is Plain Old Data without any pointers or 
references.

Cheers,
Tim