Wt

Mike Ackley wrote:

Button->clicked().connect(this,&Home::startCreateMaster);

and

Button->clicked().connect(boost::bind(&Home::startCreateMaster, this)); (found in the forums)

both fail to trigger "startCreateMaster" to start. I have tried a few other combinations without success, and despite my reading, I must be missing something. I think the issue is that the startCreateMaster is a function in the same class as the button, on the same thread. However, I don't know why the pushbutton disable would work (so that event must be getting through) but the event is not getting through to the function.

Both should work. A slot remains connected until its target is deleted (insofar that target is a boost::trackable, which is the case if it inherits from WObject).

My goal is to implement the 'home' page, with a button, that invokes a function on the Homepage Class (startCreateMaster) which will kick off a thread to create a master database.

I'd like the thread to set a finished signal when it's done, and send a signal back to the Home class.

Pay attention: if you manipulate a widget tree from within a thread, you MUST grab the UpdateLock (See WApplication documentation). Also, those modifications will not be sent to the client unless you trigger an update yourself. Look at the feature/serverpush example for more info. Also, consider using WServer::post() instead of the UpdateLock mechanism; it is usually much simpler.

Can you post a full test-case of what you're trying to acomplish? It's hard to point out the possible mistake in this way...

Best regards,
Wim.

Hi Wim,

Sorry to take a while to reply, thanks for your answer.

My lack of C++ knowledge and reading the documentation was at the core. I fixed it now.
What I originally did, was to use leverage (copy) the homepage example, with push button triggers to try and start a background thread.

I didn't realize that some of the homepage elements are wrappered as const, which don't respond
to triggers - at least when attaching functions to respond. So I moved some of the constants to be instantiated and this worked.

I studied both the server push, and the broadcast example, as well as some determined reading to understand more how virtualization works, as well as info on boost::bind, which I didn't understand before.
One further point was that I originally has a separate object with a (thread) function defined, which i instantiated from a function which was triggered. However, the object got into all sorts of scope issues.
Then I learned that you can simply run a method off the current object (homepage for example) as a separate thread, and then I simply used server.post back to update the main event loop to manipulate the widgets (progress bar). Unfortunately, because of a couple of shortfalls in my C++ knowledge, I originally made things more complex than I needed. I studied the serverpush and simplechat examples. Both seem to deal with cross-session communications, but I just needed same-session widget-tree updates from a thread.

So I was originally looking for the simplest post-back case. I just start a thread from the main event loop (i.e. push button) in the same session, and then update the progress bar. I achieved that simply by having a progress bar in the main widget tree, and have a thread which POSTS back a "% complete" message to the main tree, which then updates the bar. Works perfectly. I prefer server.post because the 'main widget tree' looks after the GUI rather than another thread getting control. I think this separates concerns better. However, that's just an opinion, and there may be more complex cases I didn't think of yet.

Thanks for your kind offer to help - I am sure I will have more questions, but now I an knee deep in trying the suggestion popups after solving the event problem I had.

Best wishes,
Mike
p.s. WT a very excellent library. I'm enjoying learning it. Thanks