Fix vobject method

src/vips/Connection.lua

@@ -23,6 +23,10 @@ Connection.new = function(vconnection)
     connection.vconnection = vobject.new(vconnection)
     return setmetatable(connection, Connection.mt)
 end
+function Connection_method:vobject()
+    return ffi.cast(vobject.typeof, self.vconnection)
+end
+
 function Connection_method:filename()
     -- Get the filename asscoiated with a connection. Return nil if there is no associated file.
     local so = ffi.cast('VipsConnection *', self.vconnection)

src/vips/Source.lua

@@ -3,17 +3,12 @@
 local ffi = require "ffi"
 
 local verror = require "vips.verror"
-local vobject = require "vips.vobject"
 local Connection = require "vips.Connection"
 
 local vips_lib = ffi.load(ffi.os == "Windows" and "libvips-42.dll" or "vips")
 
 local Source = {}
 
-Source.vobject = function(self)
-    return ffi.cast(vobject.typeof, self)
-end
-
 Source.new_from_descriptor = function(descriptor)
     local source = vips_lib.vips_source_new_from_descriptor(descriptor)
     if source == ffi.NULL then

src/vips/Target.lua

@@ -2,17 +2,12 @@
 
 local ffi = require "ffi"
 
-local vobject = require "vips.vobject"
 local Connection = require "vips.Connection"
 
 local vips_lib = ffi.load(ffi.os == "Windows" and "libvips-42.dll" or "vips")
 
 local Target = {}
 
-Target.vobject = function(self)
-    return ffi.cast(vobject.typeof, self)
-end
-
 Target.new_to_descriptor = function(descriptor)
     collectgarbage("stop")
     local target = vips_lib.vips_target_new_to_descriptor(descriptor)