Second draft (was Re: defs files)

[Havoc Pennington <hp redhat com>]

George <jirka@5z.com> writes: 
> why call function arguments "arguments" why not "parameters"
> 

OK that helps too.

ChangeLog:

- argument becomes "object-argument" or "parameter"
- use the named-attributes thing for arguments and fields; this makes
  the format extensible as long as language bindings ignore unknown 
  attribute names. i.e. avoid the positional stuff more pervasively
- varargs attribute for functions/methods/etc
- added "inoutness" to types; but I don't like this, I think 
  maybe we want instead must-free must-not-free must-initialize
  and other such less-abstract stuff. "inoutness" assumes an 
  API that's more consistent than it is
- added by-value-ok attribute to boxed
- added "access" attribute to struct/object fields



===
(module module-name
  (submodule-of module-name)) ;; submodule is optional

Ex: (module Gtk)
Ex: (module Rgb
      (submodule-of Gdk))

modules are later referred to with a list of module names, like 
(Gdk Rgb) or (Gtk)

===

(type
 (alias some-unique-identifier)
 (in-module module-name)   ;; optional, gchar* is not in a module
 (c-name name-of-symbol-in-C)
 (inoutness in-or-out-or-inout)) ;; if not specified, can deduce from
                                 ;; the C type

Ex: (type
     (alias broken-in-string)
     (c-name gchar*)
     (inoutness in))

    (type
     (alias GtkWidget**)
     (c-name GtkWidget**))

"Type" bindings are automatically assumed for objects, boxed types,
etc. as defined below.

The alias field is used to refer to the type later on.

If the C type has spaces they are converted to hyphens:
 (type
    (alias const-gchar*
     (c-name const-gchar*)))

So hyphens have to go back to spaces for binding generators that
output C code. 

===
(object object-name
   (in-module module-name-list)
   (parent object-name optional-module-name-if-different)
   (abstract boolean-is-abstract-class) ;; omit for default of #f
   (c-name name-of-the-object-in-C)
   (field (type-and-name type-alias-of-struct-field name-of-struct-field)
          (access read-or-write-or-readwrite)))
   

Ex: (object Widget
      (in-module (Gtk))
      (parent Object)      ;; could say (parent Object (Gtk))
      (abstract #t)
      (c-name GtkWidget)
      (field (type-and-name GdkWindow* window) (access read)))

An "object" declaration automatically implies the type declaration:

(type
  (alias pointer-to-c-name)
  (c-name pointer-to-c-name))

Ex: (type (alias GtkWidget*) (c-name GtkWidget*))

Of course many language binding generators can just ignore this
implicit declaration.

===

(function function-name
  (in-module module-name-list)
  (c-name function-name)
  (return-type return-value-type) ;; defaults to void
  (parameter (type-and-name parameter-type-alias parameter-name)) ;; as many of these as you want
  (varargs #t) ;; has varargs at the end
)

Ex:
  (function init
    (in-module (Gdk Rgb)
    (c-name gdk_rgb_init)))

Ex: 
  (function cmap_new
    (in-module (Gdk Rgb))
    (c-name gdk_rgb_cmap_new)
    (return-type GdkRgbCmap*)
    (parameter (type-and-name guint32* colors))
    (parameter (type-and-name gint n_colors)))

===
(method method-name
  (is-constructor boolean-is-a-constructor)     ;; omit for default of #f
  (of-object object-name module-name)
  ;; retval/arg attributes as for (function), but with first parameter omitted
  )
 
Ex:
  (method set_text
     (of-object Label (Gtk))
     (parameter (type-and-name const-gchar* str)))

===
(object-argument arg-name
   (of-object object-we-are-an-argument-of optional-objects-module)
   (type argument-type)       ;; not sure what to put for type
   ;; flags all default to #f
   (readable bool-value)
   (writeable bool-value)
   (run-action bool-value)         
   (construct-only bool-value))

Ex:
  (object-argument label
     (of-object Label (Gtk))
     (type gchar*) ;; ????
     (readable #t)
     (writeable #t))

=== 
(signal signal-name
  (of-object object-we-are-a-signal-of optional-objects-module)
  ;; return value and parameters as for a function, omitting the object
  ;; and user data parameters

  ;; what other properties matter for a signal?
)

Ex:
  (signal select_row
     (of-object CList (Gtk))
     ;; return type defaults to void
     (parameter (type-and-name gint row))
     (parameter (type-and-name gint column))
     (parameter (type-and-name GdkEvent* event)))

=== 
(enum enum-name
  (of-object objname module)  ;; in-module and of-object are mutually exclusive
  (in-module modname)
  (c-name name-in-c)
  (value (name value-name-noprefixes-hyphen-lowercase) (c-name value-c-name)))

Ex:

  (enum DirectionType
    (in-module Gtk)
    (c-name GtkDirectionType)
    (value (name tab-forward) (c-name GTK_DIR_TAB_FORWARD))
    (value (name tab-backward) (c-name GTK_DIR_TAB_BACKWARD))
    (value (name up) (c-name GTK_DIR_UP))
    (value (name down) (c-name GTK_DIR_DOWN))
    (value (name left) (c-name GTK_DIR_LEFT))
    (value (name right) (c-name GTK_DIR_RIGHT)))

  (enum Pos
    (of-object CTree (Gtk))
    (value (name c-name) (c-name GtkCTreePos))
    (value (name before) (c-name GTK_CTREE_POS_BEFORE))
    (value (name as-child) (c-name GTK_CTREE_POS_AS_CHILD))
    (value (name after) (c-name GTK_CTREE_POS_AFTER)))

===
(flags) is just like enum, but some bindings may wrap enums and flags differently.
    
===
(boxed boxed-name
  (in-module modname)
  (c-name c-name)
  (by-value-ok boolean-can-just-memcpy)
  (ref-func func-to-increase-refcount)
  (unref-func func-to-decrease-refcount)
  (copy-func func-to-copy)
  (destroy-func func-to-destroy)
  (field (type-and-name type-alias-of-struct-field name-of-struct-field)))

Ex:

 (boxed Pixmap
   (in-module (Gdk))
   (c-name GdkPixmap)
   (ref-func pixmap_ref)
   (unref-func pixmap_unref))

This implies the type alias GdkPixmap* to the C type GdkPixmap*

 (boxed Rectangle
   (in-module (Gdk))
   (c-name GdkRectangle)
   (by-value-ok #t)
   (field (type-and-name gint16 x) (access readwrite))
   (field (type-and-name gint16 y) (access readwrite))
   (field (type-and-name guint16 width) (access readwrite))
   (field (type-and-name guint16 height) (access readwrite)))

Implies GdkRectangle* type alias.

===

(user-function name
  (in-module module)
  (c-name c-typedef-name)
  ;; return-type and parameters as for (function)
)

Ex:

 (user-function PrintFunc
    (in-module (Gtk))
    (parameter (type-and-name gpointer func_data))
    (parameter (type-and-name gchar* str)))

===

(typedef new-name
  (in-module module)
  (c-name c-full-name)
  (orig-type alias-of-orig-type))

Ex:

 (typedef Type
   (in-module (Gtk))
   (c-name GtkType)
   (orig-type guint))