gtk_widget_add_accelerator with no GdkModifierType

Question

I'm trying to add an accelerator to a "Play" GTK+ 3.0 menu item using the following C code:

gtk_widget_add_accelerator(play, "activate", accel_group, GDK_KEY_F5, NULL, GTK_ACCEL_VISIBLE);

I want the "Play" menu item to be activated when the user presses the F5 key. However, when I try to compile I get the following error:

/usr/include/gtk-3.0/gtk/gtkwidget.h:504:9: note: expected 'GdkModifierType' but argument is of type 'void *'

I don't want to add a modifier, just have the menu item activate when the user presses the F5 key. I realized that I can pass a 0 as the argument (since GdkModifierType is just a binary mask), but is there a preferred way over this solution -- perhaps a preprocessor macro called GDK_NONE_MASK or something to that effect?

ulidtko · Accepted Answer · 2013-09-23T12:53:33.803

1

That's right, you're not supposed to pass pointers (e.g. NULL) to an enum parameter. Attempting to do so is wrong, and this is what the compiler told you.

You can get away with 0. Implicit conversion from ints to enums will kick in.

To be more explicit, you can write (GdkModifierType)0 as the argument.

edited Sep 23 '13 at 12:53

answered Sep 21 '13 at 22:45

ulidtko

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Is the expression `GdkModifierType(0)` a C++ specific cast? – Vilhelm Gray Sep 23 '13 at 12:47
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@VilhelmGray Correct. `(GdkModifierType)0` would be appropriate for plain C. – ulidtko Sep 23 '13 at 12:54

gtk_widget_add_accelerator with no GdkModifierType

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