[Webkit-unassigned] [Bug 16401] [GTK] GObject/C DOM binding

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=16401





------- Comment #141 from lkcl at lkcl.net  2009-02-11 06:32 PDT -------
> When are properties actually useful? They are unconfortable to use even in
> Python. For widgets, software such as Glade benefits from them, but they don�t
> seem to be so useful in the DOM. I wouldn't regret it if they dissapeared.

 i mentioned this earlier, but will repeat it here so that it is clearer,
 martin.  automated property detection in higher-level abstract classes.

 when providing an abstraction layer on top of python-pygobject bindings,
 for example, which is what pyjamas-desktop is (it's a port of GWT to python
 _and_ webkit).

 all that is needed, to replace javascript code:

 if (node.offsetWidth > 20)
 {
    Window.alert("width > 20");
 }

 is this:

 if node.offsetWidth > 20:
    ui.Window.alert("width > 20")

 that's it.  done.  finished.

 underneath, that node.offsetWidth does something like this:

 def __getattr__(self, property_name):
    return gdom_node_get_property(property_name)

 that's all.  nothing to it.  dead.  simple.

 if you REMOVE property-getting/setting, it gets xxxxing AWFUL:

 def __getattr__(self, property_name):
   s = "gdom_node_get_%s" % property_name
   return eval(s)

 that's the best "simple" case i can think of, and it's pretty bad.
  here's the much much worse-case scenario:

 def __getattr__(self, property_name):
   t = gdom_node_get_type(self, "type") # argh!  can't even get the node type!
   if t == "element":
      if property_name == 'width':
          return gdom_element_get_width()
      elif property_name == 'height':
          return gdom_element_get_height()
      ...
      ...
   elif t == '....'
      ...
      ....

   ...
   ...
   ...
   ...

 this will be about a _thousand_ lines long, and require a _nightmare_
 maintenance task as the DOM model is expanded.

 and that's just "get".  what about "set"?

 yes, you could auto-generate this... but from what?  from the original
 IDL file??

 you can't auto-generate it from the .defs file because the information
 has been lost by that point as to which bits were properties and which
 bits were truly functions.

 apologies for spelling it out like this but i hope it's clearer as to
 why it is so damn important that properties be available as properties.

 if you're doing a "simple language thing" - great, good luck, go for it,
 you will have no need for and no purpose for which getter/setter properties
 are useful.

 if however you're providing an abstraction layer on top of language
 bindings on top of  the glib/gobject bindings, then having exactly the
 same access to properties in exactly the same way that javascript has
 access to properties is utterly essential.

 l.


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