Create a closure with the given arguments. See gtk.builder.Builder.createClosure for more details on those. The C implementation will try to use dlsym() to locate the function name and then gobject.cclosure.CClosure.new_ to create a closure for the symbol. The default implementation just fails and returns null.
Try to lookup a gobject.types.TYPE_FLAG_RESERVED_ID_BIT via the given function name, specified explicitly in a GtkBuilder file, like via the "type-func" attribute in the <object> tag. This function is very rarely used. The C implementation will use dlsym() and call the resulting function as a GTypeFunc. The default implementation will fail and just return G_TYPE_INVALID.
Try to lookup a gobject.types.TYPE_FLAG_RESERVED_ID_BIT via the its name. See gtk.builder.Builder.getTypeFromName for more details. The C implementation will use gobject.global.typeFromName and if that fails try to guess the correct function name for registering the type and then use dlsym() to load it. The default implementation just tries gobject.global.typeFromName and otherwise fails.
The virtual function table to implement for gtk.builder_scope.BuilderScope implementations. Default implementations for each function do exist, but they usually just fail, so it is suggested that implementations implement all of them.