[Docutils-users] Help wanted to better understand nodes.Node.walk, and solving some issues

[Leo <fha...@go...>]

Hi,

I am in the very first experimental stage of developing a writer for Braille
printing. However, I am afraid of getting bogged down on some subtle issue.
And as I am fairly new to docutils and only a seasoned programmer, I thought
I'd better ask the friendly docutils community for help.

Here is my first attempt to get acquainted with the - excellent -
architecture of docutils:


class Writer(docutils.writers.Writer):
    def __init__(self):
        docutils.writers.Writer.__init__(self)


    def translate(self):
        self.visitor = BrailleVisitor(self.document)
        self.document.walk(self.visitor)
        self.output = " "


class BrailleVisitor(NodeVisitor):
    def __init__(self, document):
        NodeVisitor.__init__(self, document)

    def visit_document(self, node):
        print node

    def visit_paragraph(self, node):
       print node

Passed a simple txt file with two paragraphs, the output looks as follows:

<document source="test.txt"><paragraph>First
paragraph...</paragraph><paragraph>Second paragraph!</paragraph></document>
<paragraph>First paragraph...</paragraph>


The script then exits with an AttributeError as walk doesn't stop at the end
of the tree. Rather, it passes None to the dispatcher which calls
unknown_visit. The latter then tries to access a non-existing settings
attribute.

The only solution I could think of is to use walkabout with a
depart_document method raising an exception. But the html writer which I
tried to understand, doesn't work like this. So there must be a better way.
Also, I do not understand the last line of the output: after </document> the
walk should terminate. Rather, it looks as if the first paragraph is
revisited...

Any helpful comment on this is very much appreciated. I am not subscribed to
this list so please put me on cc when responding.

Thanks in advance,

Leo