CODEWITHSUNDEEP
c++qt
katang
katang

Reputation: 2774

Why Qt does not produce at least a warning for the missing slot?

I have spent some time with finding an error, in connection wit slots and signals. I copied some connect() lines from another file, and I relied on the compiler to find out which objects I need to define in my new class, so I added them. The 'this' object should not be edited, so I did not care providing the corresponding slots. The program compiles OK, an even without warnigns. But -in lack of slots- does not run.

Considering the (sometimes too) strict type checking, why does not produce Qt at least a warning? (at compile time it can know for sure, that no such slot exists.)

Upvotes: 1

Views: 233

Answers (1)

ALEXANDER KONSTANTINOV
ALEXANDER KONSTANTINOV

Reputation: 913

Actually, new functor-based connections does checking at compile-time, so in case of some invalid signal/slot the app will not even compile

So, to check it during compile time you just need to use functor-based type of connection:

connect(slider, &QSlider::valueChanged,
            doubleSpinBox, &QDoubleSpinBox::setValue);

instead of string-based:

connect(slider, SIGNAL(valueChanged(int)),
        doubleSpinBox, SLOT(setValue(int)));

You can read here in details: http://doc.qt.io/qt-5/signalsandslots-syntaxes.html

Upvotes: 5

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