Jason Heeris wrote: > On 5 July 2010 17:36, A.T.Hofkamp <a.t.hofk...@tue.nl> wrote: >> Or you could drop threads entirely, and do your async activities using the >> Twisted framework, designed for making asynchronous programs (where GTK >> event handling is just one of the asynchronous sources). > > Please don't take this as a flame, but I've had this advice before > (usually on #python), and I usually go through this process:
I was mostly triggered by the fact that you are doing asynchronous activities next to the GTK application, which are apparently complicated enough to use threads for. > 1. Look at Twisted website > 2. Only read things about twisted being a networking framework Network communication is *by* *far* the most complicated form of asynchronous communication (anything can go wrong at any moment). Obviously, a framework for asynchronous communication should put the focus there. About not mentioning guis: If you write a spread sheet program, and explain its features, you don't explain that you can add two numbers, do you? > 3. Someone corrects me, saying "Twisted is so much more!" (That may be > the case, but the fact that the website goes on and on without > mentioning this does not inspire confidence.) Twisted is technically very good, but their PR is not, let's say, optimal. Combined with the (at first) twisted way of doing things (namely event-based programming in the extreme), you are looking at a very steep learning curve. I completely agree with you that this is a weak point. I found the best source of information to be their howtos and tutorials/examples, to get the global picture, and the API documentation (for the protocols, mostly). > 4. I search the Twisted website for documentation on/examples of GTK > applications Basically, asynchronous communication means you are doing event-based programming everywhere. You are constantly waiting for something of interest to happen (the Deferreds in Twisted-speak). When the event does happen, the handler is triggered, which handles the event, and sets up new Deferreds (new handlers) for new events that may happen. From this point of view, it is totally irrelevant what event you get (a network comm event, a GUI event, or something from another source), only the actual handler of the event needs to know details of the event. The Twisted main-loop (reactor) only needs to know that it should watch for GTK+ events too, so you need a gtk2reactor instead of a normal one. See also http://twistedmatrix.com/documents/current/core/howto/choosing-reactor.html#auto11 That page also refers to an example "doc/core/examples/pbgtk2.py" From a complexity point of view, there is very little that can go wrong with event handling in a GTK gui, so little need to discuss things at length. > 5. I give up and search the Twisted website for documentation > on/examples of *any* non-network based applications As I tried to explain above, to Twisted *everything* is an event that is waited for, and when it happens, it should be handled. There is no difference between network-based events and non-network-based events. They are all done using Deferreds that fire when the event happens. In the same way, Twisted does not care about the comm protocol use to deliver the event. Whether a user pressed a button at a web-form, or sent a IRC message does not matter for computing the response. > 6. I give up and search the greater web for documentation on/examples > of Twisted GTK applications > 7. I give up on Twisted and find another way. > > Really, I would love to get a grip on Twisted. It seems really useful. > But I've still not found any kind of stepping stone into it. Please, > please, please if you know of one, post it so I can add another tool > to my belt. I will rescind everything I've said here and then some. I'd recommend to get to grips with the Deferreds using a communication protocol example, as those are around. Once you get how events are done, apply it to gtk events. > (Since the Twisted website is currently down, I can't tell if things > have changed and I should get over it and have another try.) It's up again (or was, at least). It has not changed much, at first sight. I am not sure why there is so little nice introductory information. I think it is because the gap between both worlds is so big. Either you don't get it, and then you cannot write about it due to lack of understanding, or you do get it, and then you cannot imagine how to explain it to somebody that doesn't. (Like programming, can you explain the essence of what programming is, to somebody that has no clue about computers?) Albert _______________________________________________ pygtk mailing list pygtk@daa.com.au http://www.daa.com.au/mailman/listinfo/pygtk Read the PyGTK FAQ: http://faq.pygtk.org/
