W3C home > Mailing lists > Public > www-dom-ts@w3.org > June 2003

Making TS work in Python (and an L2 suite bug)

From: Andrew Clover <and-w3@doxdesk.com>
Date: Wed, 18 Jun 2003 12:50:33 +0000
To: www-dom-ts@w3.org
Cc: carnold@houston.rr.com
Message-ID: <20030618125033.GA18541@doxdesk.com>

Curt Arnold <carnold@houston.rr.com> wrote in www-dom list <www-dom@w3.org>:

> If you'd like to take a shot at manually coverting some of the generated 
> Java or Javascript tests, I'd be willing to create a variant of the 
> existing stylesheets to produce Python tests.

OK, here's what you'll need to know to produce a Python transformation.

Variables do not have to be declared. Unless a <var> specifies an initial
value it can be completely ignored.

String and integer literals are the same as ECMAScript. List literals can
be written as '['...value...','...value...']'.

null literals are 'None'. Boolean literals are 'True' and 'False', but if you
want to be compatible with Python 2.1 you'll want to use '1' and '0' instead.
If may be easiest just to add something like:

  null= None
  true= None is None
  false= None is not None

at the start of each test, then you can use null/true/false in expressions
as normal.

method calls are the same as Java and ECMA:

  document.createElementNS(None, "foo")

property access is direct, not through getters/setters:

  root= document.documentElement
  textNode.data= "foo"

Equality comparison uses the usual '=='/'!=' operator. Same-object comparison
uses the 'is'/'is not' operator. Checking whether an instance implements an
interface can't really be done; you can check whether something is a subclass
instance using isinstance but that's all.

Addition is the usual '+' operator. Logical negation is the 'not' unary
operator. Appending to a list can be done with the append method:


and getting the length of a list is done using the len() function:

  ncomments= len(comments)

There's no standard for loading documents (until L3 L/S), some sort of
factory stuff will be needed for <load>, eg.

  from xml.dom import minidom
  factory= minidom.parse
  import os.path
  document= factory(os.path.join("files", "staff.xml"))

<for-each> comes out as:

  for membervar in collection:
    ...indented loop body...

<if><else/></if> comes out as:

  if condition:
    ...indented body...

The indent level must be consistent. Don't know if that might be a problem
with XSLT.

Exceptions are caught using:


You can't really tell whether the exception that was thrown was a
DOMException or something else as DOMException is not bound to anything
in particular. You could try:

  exception= None
  except Exception, e:
    if hasattr(e, code):
      exception= e.code

to pass non-DOM errors through.

I think that covers everthing TSML needs.

I've knocked up a quick and (very) dirty Python TSML interpreter which can
run most L1 and L2 Core tests, to check my own imp; you're welcome to a copy
if it'd help.

Anyway, the imp passes L1 modulo the setting-a-readonly-node's-nodeValue-
when-it-is-defined-as-null tests, where I simply cannot agree with the TS's
strange interpretation of the spec. It's currently making its way through
L2, not helped by me having downloaded an old version of the suite which is
full of bugs. Looking at CVS I see at least this one remains, in

  <getNamedItemNS var="entity" obj="entities" namespaceURI="null"
  ...same for notation...

Entities and notations shouldn't be gettable by NS methods as their
localNames are null. Hence the entity variable gets set to null, and an imp
is entitled to throw an implementation-dependant exception (re L1 SE 1.2)
instead of a HierarchyRequestErr.

I note the native-Java expressions seem to have gone, though, hurrah.

Andrew Clover
Received on Wednesday, 18 June 2003 09:00:54 UTC

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