getting NumericMenuItem value in callback

[dgbalharrie]

The menu is working nicely, but I can't seem to get the value that has been edited in NumericMenuItem in the callback. get_value() isn't available. If I change the parameter in the callback from MenuItem to NumericMenuItem it actually works, but I don't think this is correct. Looking at the forums, I see others asking the same question but no answers.

[jonblack]

You'll need to cast the value passed in to the callback:

void on_item_selected(MenuItem* p_menu_item)
{
    NumericMenuItem* p_nmi = dynamic_cast<NumericMenuItem*>(p_menu_item);
    Serial.println(p_nmi->get_value());
}

Make sure that the callback really is for a NumericMenuItem, otherwise you'll get a runtime error.

[dgbalharrie]

Thank you for the information. However I get a compile error: 'dynamic_cast' not permitted with -fno-rtti I have searched, but I can't find how you can change this option.

[jonblack]

Ah sorry, there's no runtime-type information on the Arduino, so you can't use dynamic_cast. You'll have to do a c-style cast instead:

NumericMenuItem* p_nmi = (NumericMenuItem*) p_menu_item;

[dgbalharrie]

That compiles ok. Thank you. I also realised that I know the objects in the callback and can access the objects directly which works as well as they are global on the arduino. Thank you - you can close the issue.