Re: How to call WebKit.DOMDocument.evaluate function in python

[Niranjan Rao <nhrdls gmail com>]

Thanks for the information. I had came across the webkit bug you mentioned.

And yes, I had tried creating empty WebKit.DOMXPathResult object and 
passing it. Did not work.

As much as I hate this, I see only following options for me now. As much 
as I would have loved it, only python based solution may not be possible.

1. Write my own c extension - pain to distribute, need to worry about 
lot of things or user needs to build it.
2. Switch to another language where this works - e.g. java
3. Try using "internal" variables and see if it works. If not, back to 
square one again :(

I have logged a bug against Webkit GTK team also.

Regards,

Niranjan

On 07/02/2013 04:58 AM, Simon Feltman wrote:
> Hi,
>
> On Mon, Jul 1, 2013 at 11:48 PM, Niranjan Rao <nhrdls gmail com 
> <mailto:nhrdls gmail com>> wrote:
>
>     I need to perform some DOM operations once the document is loaded.
>     Webkit
>     DOMDocument provides evaluate method which can allow me to reach
>     to element
>     using xpath,  if it works. The parameter DOMXPathResult of the
>     evaluate
>     method has annotations declared in such a way that null/None value in
>     python can not be used.  However null value in this case is legal and
>     accepted.
>
> It looks like the introspection bindings are missing (allow-none) for 
> the parameter. The bindings seem to be generated by a perl script and 
> a quick web search revieled a related problem here: 
> https://bugs.webkit.org/show_bug.cgi?id=42115
>
> You should probably log a bug against WebKit Gtk to get the annotation 
> fixed. Also, have you tried creating an empty WebKit.DOMXPathResult 
> and passing that?
> >>> res = WebKit.DOMXPathResult()
>
>     Is there any way to get underlying gobject pointer from python so
>     that I
>     can use ctypes and try to call function directly. So far my
>     attempts have
>     resulted in coredump as webkit is asserting on various values I am
>     sending
>     to it.
>
>
> Later versions of PyGObject give access to the internal GObject 
> pointer through the "__gpointer__" attribute on wrapped objects. But 
> it is unclear if this would be useful in ctypes because it returns a 
> PyCapsule. This attribute is used internally for some parts of 
> PyGObject. However, we cannot support this officially as it is an 
> implementation detail, so use at your own risk.
>
> You should also be able to create a small C extension to Python which 
> wraps the function up for you.
>
> -Simon