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Can Qt signals be public or private? Can I create internal signals, which are seen only inside the class?
Update: I have a class with some internal signals. How can I make those signals invisible for other classes (encapsulation & information hiding)?
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Signals are public access functions and can be emitted from anywhere, but we recommend to only emit them from the class that defines the signal and its subclasses.
In C++, public means those members that are accessible from anywhere where the object is visible, private means that members are accessible only from within other members of the same class or from their friends. But in Qt, the difference in private slots and public slots seem not to exist.
The Qt signals/slots and property system are based on the ability to introspect the objects at runtime. Introspection means being able to list the methods and properties of an object and have all kinds of information about them such as the type of their arguments.
there is no harm with using slot as a private member, if you are making use of those slots within the same class. it is just a normal member function there is nothing more than normal function... but if you want use those slot outside of the class then you should declare as a public slots.
No. Signals cannot be public or private. Qt signals are protected class methods.
"signals" keyword is defined in qobjectdefs.h (line 69 as for Qt 4.6.1):
# define signals protected UPDATE: signals are only protected upto and including all minor versions of Qt 4. From Qt 5.0 onwards they are public. See https://stackoverflow.com/a/19130831.
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