[lxml-dev] Pickling objectified trees

[Christian Zagrodnick]

Hi,

the other day I had to pickle objectified trees. I just thought to 
share my findings.

Pickling is about serialization. IMHO the natural serialization of an 
objectified tree is its XML representation. So the following basically 
does that:

--------------------------
import copy_reg

import lxml.etree
import lxml.objectify


def treeFactory(state):
    """Un-Pickle factory."""
    return lxml.objectify.fromstring(state)

copy_reg.constructor(treeFactory)


def reduceObjectifiedElement(object):
    """Reduce function for lxml.objectify trees.

    See http://docs.python.org/lib/pickle-protocol.html for details.
    """
    return (treeFactory,
            (lxml.etree.tostring(object), ))

copy_reg.pickle(lxml.objectify.ObjectifiedElement,
                reduceObjectifiedElement,
                treeFactory)
-----------------------------------------


You might consider just registering the reduce function in lxml itself. 
Shouldn't hurt, should it.


-- 
Christian Zagrodnick

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