[mcclim-devel] arglist, tester-arglist, and doc-arglist for presentation translators

[Max-Gerd Retzlaff]

Hello,

please have a look at 23.7.1 of the CLIM 2.0 specification. In the section
about DEFINE-PRESENTATION-TRANSLATOR it says:

   "arglist, tester-arglist, and doc-arglist are each an argument list
   that must "match" the following "canonical" argument list.
      (object &key presentation context-type frame event window x y)
   In order to "match" the canonical argument list, there must be a
   single positional argument that corresponds to the presentation's
   object, and several named arguments that must match the canonical
   names above (using string-equal to do the comparison)."

They are defined in the same way for
DEFINE-PRESENTATION-TO-COMMAND-TRANSLATOR, DEFINE-PRESENTATION-ACTION,
and DEFINE-DRAG-AND-DROP-TRANSLATOR, with the only exception that the
doc-arglist "includes a named (keyword) stream argument as well".

If my interpretation is correct, you have not only to use theses names
*literally* (because of the STRING-EQUAL requirement), but also the
empty list is not allowed and the first argument is always required
and has to be (STRING-EQUAL to) OBJECT.


I added an ASSERT to beginning of CLIMI::MAKE-TRANSLATOR-LL because
I've made the error earlier to try to bind the object to a symbol
non-equal to OBJECT, and I've seen that there are presentation
translators in beirc that just try to bind PRESENTATION. The ASSERT is:

  (assert (string-equal (car translator-args) "object")
          ()
          "The first parameter of the presentation translator's argument list~%has to be STRING-EQUAL to OBJECT. (See 23.7.1)")

Well, afterwards McCLIM doesn't compile anymore. There are two
presentation to command translators in dialog.lisp: COM-EXIT-BUTTON
and COM-ABORT-BUTTON.

After I allowed also the empty arglist it still did not compile
because (at least) the presentation to command translator
COM-DESCRIBE-PRESENTATION-TRANSLATOR has the list (presentation) as
its arglist as well as its tester-arglist.


Personally I think the requirement that the arglists have always to be
at least the list (object) (if I interpret the spec correctly) is
quite odd. There are perfectly reasonable cases to have an empty list:
E.g. COM-EXIT-BUTTON doesn't need the object itself. And likewise
COM-DESCRIBE-PRESENTATION-TRANSLATOR doesn't need the object but only
the presentation.

Why should OBJECT be bound if it isn't used at all?  The way
DEFINE-PRESENTATION-TRANSLATOR and its friends are specified you
cannot insert a DECLARE IGNORE (or IGNORABLE), and that means you
would always get style warnings on SBCL in these cases.


The "canonical" argument list should be the following in my opinion:
  (&key object presentation context-type frame event window x y)
And also the empty list should be considered to match it.


What do you think? Should we just CLIMI::MAKE-TRANSLATOR-LL leave as
it is, and add this to a list of known but wanted nonconformances to
the CLIM specification?

Bye,
Max

-- 
Max-Gerd Retzlaff <m.retzlaff at gmx.net>

For your amusement:
People who claim they don't let little things bother them have never
slept in a room with a single mosquito.
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