[PD] Changing Send/Receive Names After Instantiation

[Christof Ressi]

Haha, what I wanted to say is that if you're worried about the danger of 
using [iem_receive], then dynamically destroying [r] is not a solution 
because it is just as dangerous because the destructor of [r] will 
unbind the symbol.

An easy way to avoid this problem on the user side is to always use a 
clock for the message that is going to unbind the symbol. E.g. the 
following is always safe:

... -> [del 0] -> [set foo( -> [iem_receive]

The reason is that [del 0] breaks the message passing chain and executes 
the messages downstream at the beginning of the next scheduler tick. 
Same thing for dynamically deleting objects.

Don't worry too much. If you've been using [iem_receive] and dynamically 
deleted objects and didn't experience a crash, it probably means you're 
using it in more or less safe ways. It's just something to keep in mind 
for your next patch :-)

Christof


On 25.03.2020 22:16, oliver wrote:
> Christof Ressi wrote:
>> Check out the following discussion on GitHub: 
>> https://github.com/pure-data/pure-data/pull/604
>>
>> TL;DR: if you unbind a symbol from a receiver while sending to the 
>> symbol, Pd can crash because you modify the bind list while iterating 
>> over it.
>>
>> Personally, I've been using [iem_receive] in some projects and didn't 
>> run into problems, but only because I avoid the case described above. 
>
> Thanks Christof for the explanation !
>
> @IOhannes: i think this should be noted in the helpfile.
>
>
>> Dynamically destroying objects is even more dangerous ;-)
>
> Bummer ... another thing i do quite often ;-)
>
> Since i am not a programmer: how would i decode that twinkle emoji in 
> your sentence ?
>
> does it mean:
>
> a.) be happy that you survived so far, because you're really on mined 
> territory here ...
>
> b.) i know it's not encouraged, but as long as you don't tell anybody ...
>
>
>
> sorry ... getting a little anxious these days ...   ;-)
>
> best
>
> oliver
>
>
>
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