# Use of qt.Signal leads to a crash on exit

**URL:** <https://discourse.slicer.org/t/use-of-qt-signal-leads-to-a-crash-on-exit/8321>\
**Category:** Development\
**Created:** [September 6, 2019, 12:16pm UTC](https://discourse.slicer.org/t/use-of-qt-signal-leads-to-a-crash-on-exit/8321 "2019-09-06T12:16:54Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [June 4, 2020, 3:05pm UTC](https://discourse.slicer.org/t/use-of-qt-signal-leads-to-a-crash-on-exit/8321/4 "2020-06-04T15:05:55Z")

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Would you like to emit another object’s _signal_? This was explicitly prohibited in Qt4 but to allow new syntax in Qt5 this cannot be prevented anymore. Still, it should not be done, as you would essentially lie about the internal state of the other object to all connected objects. Objects should always emit their own signals only. Objects can call other object’s _slots_.

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