get object from property does not make a reference

[John Cupitt]

When I fetch a GObject from a property it doesn't seem to make a reference, or drop a reference on GC. For example:

x = op.property("out").get_value

where op is a GObject which has a property called "out" whose value is another GObject.

After this line, I'd expect (I think?) x to point to the value of out, I'd expect that GObject to be reffed, and I'd expect that ref to be dropped if I do:

x = nil
GC.start

Assuming nothing else is holding a pointer to that object.

Complete test program, for reference:

#!/usr/bin/ruby 

require 'gir_ffi'

GirFFI.setup :Vips
Vips::init($PROGRAM_NAME)
Vips::cache_set_max 0
op = Vips::Operation.new "jpegload"
op.set_property "filename", "/data/john/pics/k2.jpg"
puts "** objects before build:"
Vips::Object::print_all

op2 = Vips::cache_operation_build op
puts "** objects after build:"
Vips::Object::print_all

GObject::Lib.g_object_unref op
op = nil 

out = op2.property("out").get_value

op2.unref_outputs

op2 = nil 
GC.start

puts "** objects after running operation:"
Vips::Object::print_all

out = nil
GC.start

puts "** objects after tidy up:"
Vips::Object::print_all

[John Cupitt]

I think I have this completely confused. I'll close and try again when I have a better question.