OpenEuphoria

Re: Callbacks

• Posted by Robert Craig <rds at ATTCANADA.NET> Sep 13, 1999
• 419 views

Greg Harris writes:
> I'm working with dynamic subclassing and would like to
> know if when I am done with a previously defined callback
> can I use free() to clear it? Or will this do bad things.. I have
> already restored the old callback using SetWindowLong.

free() can only be used to free a block of memory allocated
using allocate() or allocate_string(). If you try to free a
callback address, it might work most of the time, but don't
count on it always working.

callback() returns an address that you can use to call
a Euphoria routine from Windows or a C routine.
callback() allocates some memory for this, but it's a small
amount - about 80 bytes. Once you get a callback address
for a Euphoria routine, you can use it for the rest of the program.
I don't see much need for freeing this space. If you have
a hundred different callback routines, you only need 8000 bytes.

Regards,
   Rob Craig
   Rapid Deployment Software
   http://www.RapidEuphoria.com