Kuba Ober wrote: > Tell you what. The amount of time this discussion has taken so far I > presume is comparable to what it takes to use the working and tested > QProcess. And this will work on Windows (for those who compile LyX > with Qt/Win) as well. > > What's so bad about QProcess?
You really want to know? (In truth I know nothing about QProcess. I did investigate QEventLoop though.) 1. QEventLoop is specific to Qt >= 3.1. 2. Qt < 3.1 must use a timer with timeout set to 0. Together these two mean a lot of nasty #ifdef nastiness. See the sample code I posted here: http://article.gmane.org/gmane.editors.lyx.devel:34552 3. I have to hack the event loops in all of the different frontends to get it to work. That ends up as a *lot* of code. 4. At least for Qt < 3.1 the event loop is permanently busy even when no events are present. 5. I could replace all that nastiness by using the timeout that we already use to blink the cursor (or is that a bark ;-). Result is within the main event loop automatically and the code is trivial: + if (buffer_) { screen().toggleCursor(*bv_); + + // Use this opportunity to deal with any child + // processes that have finished but are waiting + // to communicate this fact to the rest of LyX. + ForkedcallsController & fcc = ForkedcallsController::get(); + if (fcc.processesCompleted()) + fcc.handleCompletedProcesses(); + } + cursor_timeout.restart(); } Note that this is frontend-agnostic. It 'just works'. It will also do so on Win32. All the noise has been concerned with the 'other end' of the handling in which we use the handler connected to a SIGCHLD signal to reap the zombie and to fill a global store with the pid and status of the completed child process. It's quite hard to do that *safely* and not helped by the fact that I was learning as I went. This part will not work on Win32 but it is now maximally efficient and elegant on a Posix system. I guess that the Win32 code will use a timer to periodically check whether any child processes have been completed, but really I know nothing about Win32. Any insights welcome. > No offense meant :) None taken. > Cheers, Kuba -- Angus
