[haiku-3rdparty-dev] Re: Problem sending/receiving app defined msgs
- From: Michael Pfeiffer <michael.w.pfeiffer@xxxxxxxxx>
- To: haiku-3rdparty-dev@xxxxxxxxxxxxx
- Date: Sun, 5 Dec 2010 12:44:00 +0100
Am 05.12.2010 um 12:09 schrieb Stephan Assmus:
> Hi,
>
>> Am 04.12.2010 um 23:52 schrieb Axel Dörfler:
>>
>>> hudsonco1@xxxxxxx wrote:
>>>> Thanks, I used be_app->WindowAt(0), which works because there is only
>>>> one window.
>>>
>>> The scripting solution is only for windows in other teams (that's what
>>> probably everyone assumed looking at your snippet). If you are in the
>>> same address space, you usually know your window, be it either because
>>> you remember its pointer on creation or, as you did, just use
>>> BApplication::WindowAt(). So that solution is perfectly fine, just the
>>> rest of the code looks then pretty complicated :-)
>>
>> Unless this has changed in Haiku, using WindowAt() is not thread-safe.
>> The returned BWindow object could already have been deleted when you
>> try to access it.
>> So it is (was at least in BeOS) recommended to use a BMessenger even
>> in the same application, because it checks if the target is still
>> valid before sending a message.
>
> If you use the BWindow pointer for anything else than sending a message, you
> are right. However, sending a message involves (no matter which way you do
> it) to lock the global BLooper list and to check if the looper is still valid
> before accessing any stale pointer.
It's a kind of magic ;)
Thanks for the clarification. AFAICT this is not documented in the BeBook.
Bye,
Michael
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