Changeset 25883 in project for release/4/dbus/trunk/dbus.scm

Timestamp:

02/09/12 23:55:44 (9 years ago)

Author:

ecloud

Message:

Added "boxed" variant type and unsupported type to distinguish from #f.

You can choose whether to have variants automatically unboxed when reading, or not.
But the enclosing record will be necessary to indicate to e.g. dbus:send that
you wish to send an item in a variant.

File:

• release/4/dbus/trunk/dbus.scm (modified) (3 diffs)

release/4/dbus/trunk/dbus.scm

@@ -12 +12 @@
               dbus:discover-api-xml
               dbus:dbus-service
-              dbus:type-uint32
               dbus:session-bus
               dbus:system-bus
               dbus:starter-bus
               dbus:known-bus-count
-              dbus:register-path)
-        (import scheme chicken
+              dbus:register-path
+                  unsupported-type?
+                  unsupported-type-signature
+                  variant?
+                  variant-data
+                  make-variant
+                  auto-unbox-variants)
+        (import scheme chicken extras
                 (except foreign foreign-declare)
                 foreigners
@@ -35 +40 @@
         static DBusError err;
 <#
+
+;; A disjoint type to represent any kind of dbus data type
+;; which this egg so far does not support.  The signature
+;; is the ASCII string to represent that type on-the-wire.
+(define-record-type unsupported-type
+        (make-unsupported-type signature)
+        unsupported-type?
+        (signature unsupported-type-signature))
+(define-record-printer (unsupported-type d out)
+        (fprintf out "#<unsupported-type ~a>" (unsupported-type-signature d)))
+
+;; Scheme is a dynamically typed language, so fundamentally we don't
+;; have a use for the "variant" concept; but since dbus has a variant type,
+;; we need a way of representing one when preparing a message for marshalling.
+;; So, it might as well be symmetric, putting any variant returned from
+;; a dbus call into this type as well.
+(define-record-type variant
+        (make-variant data)
+        variant?
+        (data variant-data))
+(define-record-printer (variant v out)
+        (fprintf out "#,(variant ~S)" (variant-data v)))
+;; If unboxing is turned on, when a "call"ed dbus service method
+;; returns a variant, it will look as if it was not packaged in a variant at all.
+;; By default this feature is turned off, in the interest of having a
+;; representation that is the same as you will need to build when
+;; you want to send (marshall) a dbus message.
+(define auto-unbox-variants (make-parameter #f))
 
 ; Would want to do this:
@@ -392 +425 @@
                                         (iter->pair (make-sub-iter iter))]
                                 [(eq? type dbus:type-variant)
-                                        ((make-sub-iter iter))]
+                                        (if (auto-unbox-variants)
+                                                ((make-sub-iter iter))
+                                                (make-variant ((make-sub-iter iter))))]
                                 ;; unsupported so far (not understood well enough):
                                 ;;      dbus:type-object-path and dbus:type-signature
                                 ;; dbus:type-invalid is returned as #f (could be (void) but that
                                 ;; would be the termination condition for the iterator)
-                                ;[else (format "unsupported-~c" (integer->char type))] )))
-                                [else #f] )))
+                                [else (make-unsupported-type (integer->char type))] )))
 
         (define (make-sub-iter iter)