[gdbus-codegen] handle property set on the service-side

[Gabriel LUCAS <gabriel lucas smile fr>]

Hi everyone,

I am developing a DBus service with GDBus. To avoid the repetitive and 
fastidious task of wrapping the dbus signals, properties and method call 
handling, I am using gdbus-codegen to generate the wrapper from a XML 
introspection file.

I think I might have reached some limitation with this method while 
trying to handle a property set from the service side. The generated 
code provides a vtable for the interface with the property_get and 
property_set handlers set. When a property set is received, the GObject 
property is automatically changed without having to be handled by the 
developer.

My opinion is that the service should be able to refuse a property set 
in some cases. For example, a property GNSSEnabled can be set true to 
activate the GNSS output only if the modem is powered on. Then, I'll 
need to return an error and prevent the property set if the modem is 
off.

My questions are:

1) Is there a way to do that that I haven't found (with gdbus-codegen 
generated files) ?
2) Should I avoid refusing a property set and use a method call instead 
to enable the output ?
3) Is it a feature to be added to gdbus-codegen ?

Best regards,
Gabriel Lucas