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bug#20193: 25.0.50; declarative type specification for D-Bus args
From: |
Daiki Ueno |
Subject: |
bug#20193: 25.0.50; declarative type specification for D-Bus args |
Date: |
Wed, 25 Mar 2015 12:31:33 +0900 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) |
Severity: wishlist
Hello Michael,
While using dbus.el, I found it a bit cumbersome to specify type symbols
for the arguments of dbus-call-method and dbus-send-signal.
Suppose a simple D-Bus signature "a{si}". Since dbusbind treats positive
integers as uint32, one would need to write:
(dbus-call-method :session
"org.example.Foo"
"/org/example/Foo"
"org.example.Foo"
"Test"
'(:array
(:dict-entry :string "a" :int32 1)
(:dict-entry :string "b" :int32 2)))
This is simple if the arguments are "fixed", but if one wants a wrapper,
she would need to write a loop by herself.
(defun example-foo (alist)
(dbus-call-method :session
"org.example.Foo"
"/org/example/Foo"
"org.example.Foo"
"Test"
(list :array
(mapcar (lambda (entry)
(list :dict-entry
:string (car entry)
:int32 (cdr entry)))
alist))))
So I would like to propose an alternative syntax, similar to the `:type'
keyword of `defcustom', like this:
(dbus-call-method :session
"org.example.Foo"
"/org/example/Foo"
"org.example.Foo"
"Test"
'(:type (:array (:dict-entry :string :int32)))
'(("a" . 1) ("b" . 2)))
That is, if a type symbol is a cons cell and the car is :type, treat the
cdr as the type specification of the following value.
The the wrapper can be written as:
(defun example-foo (alist)
(dbus-call-method :session
"org.example.Foo"
"/org/example/Foo"
"org.example.Foo"
"Test"
'(:type (:array (:dict-entry :string :int32)))
alist))
Would this kind of change be considered? As a proof-of-concept, I'm
attaching a small Elisp snippet that augments the argument value with
the given type information (though I guess it should be implemented in
the C level, to avoid duplication of signature computation code).
Comments appreciated.
Regards,
--
Daiki Ueno
;; (setq lexical-binding t)
;; (dbus--annotate-arg '(:array :int32) '(1 2 3))
;; ;=> ((:array :int32 1 :int32 2 :int32 3))
;; (dbus--annotate-arg '(:array (:dict-entry :string :int32)) '(("a" . 1) ("b"
. 2)))
;; ;=> ((:array (:dict-entry :string "a" :int32 1) (:dict-entry :string "b"
:int32 2)))
;; (dbus--annotate-arg '(:struct :object-path (:array :signature) :string)
;; '("path" ("sig") "password"))
;; ;=> ((:struct :object-path "path" (:array :signature "sig") :string
"password"))
(defun dbus--annotate-arg (type arg)
(pcase type
((and basic (or :byte :boolean :int16 :uint16 :int32 :uint32
:double :string :object-path :signature :unix-fd))
(list basic arg))
(`(:array ,elttype)
(list (cons :array (apply #'nconc
(mapcar (lambda (subarg)
(dbus--annotate-arg elttype subarg))
arg)))))
(`(,(and symbol (or :variant :struct)) . ,memtypes)
(list (cons symbol (apply #'nconc
(cl-mapcar
(lambda (memtype subarg)
(dbus--annotate-arg memtype subarg))
memtypes arg)))))
(`(:dict-entry ,keytype ,valtype)
(list (cons :dict-entry (nconc (dbus--annotate-arg keytype (car arg))
(dbus--annotate-arg valtype (cdr arg))))))
(_ (error "Unknown type specification: %S" type))))
- bug#20193: 25.0.50; declarative type specification for D-Bus args,
Daiki Ueno <=