Re: Ada OpenGL question

[Olivier Scalbert <olivier.scalbert@algosyn.com>]

Ludovic Brenta wrote:

> In your example, Expose'Access presumably designates a procedure.
> This is wrong.  Expose should be a function returning Boolean.  The
> return value means:
> 
> False: pass the signal to any other signal handlers attached to it
> True: abort processing of the signal.
> 
> The same holds for delete_event and a few other signals as documented
> in the GTK+ reference at http://www.gtk.org.
> 
> The GtkAda signal handler infrastructure makes it impossible to detect
> the type mismatch at compile time, so it has run-time checks instead.
> This is the source of the error message.
> 
> HTH
> 
> --
> Ludovic Brenta.

Thanks for your help Ludovic!

I do not know how to solve it.
I have tried to change the Expose procedure into a function returning a 
Boolean, but then it does not compile anymore:

gtkgl.adb:89:66: no candidate interpretations match the actuals:
gtkgl.adb:89:87: expected type "Handler" defined at 
gtk-marshallers.ads:355, instance at gtk-handlers.ads:915, instance at 
line 68
gtkgl.adb:89:87: found type access to function "Expose" defined at line 89
gtkgl.adb:89:87:   ==> in call to "To_Marshaller" at 
gtk-handlers.ads:939, instance at line 68
gtkgl.adb:89:87:   ==> in call to "To_Marshaller" at 
gtk-handlers.ads:934, instance at line 68
gtkgl.adb:89:87:   ==> in call to "To_Marshaller" at 
gtk-handlers.ads:930, instance at line 68
gtkgl.adb:89:87:   ==> in call to "To_Marshaller" at 
gtk-handlers.ads:926, instance at line 68
gtkgl.adb:89:87:   ==> in call to "To_Marshaller" at 
gtk-handlers.ads:922, instance at line 68
gtkgl.adb:89:87:   ==> in call to "To_Marshaller" at 
gtk-handlers.ads:918, instance at line 68

Olivier