[Development] QtCS - QtCore discussion

Milian Wolff mail at milianw.de
Thu Aug 22 16:15:13 CEST 2013


On Friday 26 July 2013 13:37:01 Thiago Macieira wrote:
> - exception-safety: we discussed a bit and we ended up concluding that:
> 	=> we will roll back exception safety support in all of Qt <=
>   that is, we will stop promising any level of exception safety, even in the
> tools classes.

We were asked this yesterday and wanted to ask for clarification of this 
point. While many points in Qt are plain impossible to be fixed when 
exceptions are thrown in some cases (e.g. containers etc.), what about such 
cases like throwing an exception in a slot which is mentioned in the wiki 
(which apparently crashes)? In general, would it be accepted to add more RAII 
patterns to Qt codebases where appropriate to guard against exception safety 

Generally, I assume it's OK for a developer using Qt to throw exceptions. But 
at what point is he required to catch? What are the guidelines here? Must he 
ensure that no exceptions are thrown across Qt functions? I.e. never throw 
from a slot? I'd welcome if this could be clearly communicated somewhere in 
the documentation. People will use exceptions and they will run into problems 
when using Qt, so this must be clarified imo.

Milian Wolff
mail at milianw.de

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