Without a dll, one could probably achieve something with DDE but DDE isn't really the best way to go about it.
DDE would very likely be too slow in most scenarios. A global mutex is probably the best method. An alternative method would be to lock the file for exclusive access (although I am not sure how atomic that is). Currently, /fopen does not support an exclusive access switch. I have added /fopen -x to do this in the next version. If a file is already in use, /fopen -x will fail. This can be used to create generic lock files for shared resource access.
As far as mIRC scripters are concerned, that's their problem smile but I'm curious, what was mIRC doing before and what is it doing now? aren't INI file in memory anyway, wasn't the problem just flushing to disk?
If you are referring to the bug reported in this thread, the crash was due to a multi-threading issue when attempting to access a file that was already in use. This is the issue that has been fixed. However the issues related to multiple applications accessing the same INI file simultaneously will still be present.
