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ENH: Add Python compatibility to query and retrieve widget #1064

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@cpinter cpinter commented Jan 25, 2023

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@lassoan lassoan left a comment

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It looks OK but need to clarify the database object ownership.

return;
}

d->RetrieveDatabase = QSharedPointer<ctkDICOMDatabase>(dicomDatabase);;
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extra ;


public Q_SLOTS:
void setRetrieveDatabase(QSharedPointer<ctkDICOMDatabase> retrieveDatabase);
void setRetrieveDatabase(ctkDICOMDatabase* dicomDatabase);
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Need to describe who owns the dicomDatabase object after this call.

return;
}

d->RetrieveDatabase = QSharedPointer<ctkDICOMDatabase>(dicomDatabase);;
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As I understand, ownership of the database is passed to this widget (the widget will delete the object when it is destroyed). This would be unexpected and have quite high chance of double-delete.

Maybe we could fix this by setting a custom deleter function that does not actually delete the object (does not do anything).

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I didn't consider this. What I'm not sure about is the reason to use a QSharedPointer in the first place. I thought about making it a simple pointer but it may break the API and didn't want to do that. Not sure what you think about this.

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@lassoan lassoan Jan 28, 2023

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Shared pointer makes sense because the database ownership is complicated (it may be used without a widget or used by multiple widgets) and it is very important to cleanly delete it during application exit. Unfortunately, shared pointer support has not been implemented in PythonQt, so we need workarounds.

Search for skipDelete in this repository for how a dual mode use is inplemented in another class.

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