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Thread: execution of slots

  1. #1
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    Default execution of slots

    hi all,

    i have connected a signal A with a slot T and i would like to know what would happen if:

    1) A is fired -> T is invoked the first time
    2) A is fired again, while the first call of T still is in progress

    now, does qt start the slot T directly such that several "instances" of the method are running
    or does it wait until the first invocation of T terminates???

    (by the way, it is a simple GUI, no multi-threaded app)

    thanks

    smalls

  2. #2
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    Default Re: execution of slots

    Quote Originally Posted by smalls
    now, does qt start the slot T directly such that several "instances" of the method are running or does it wait until the first invocation of T terminates???
    Direct connections behave just like function calls. Every time you emit a signal, Qt will call the first connected slot, when it returns second slot will be invoked and so on. If there is an emit statement inside a slot, Qt will start invoking apropriate slots immediately.

    Queued connections behave like custom events from Qt3 --- emit statement posts an event to apropriate event queue and slot is invoked when that event loop picks up this event.

  3. #3
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    Default Re: execution of slots

    Since you are single-threaded the calls are done imediately by the main / GUI thread. That means emit calls the slots one after the other - only the order is undefined.

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