The inheritance of @xml:lang and @xml:base creates a lot of
complexities for an implementation. When they are used in combination
with atom:source, things get particularly bad.
Should we add some notes to the spec to remind people how to correctly
handle base and lang when atom:source-ifying entries?
A couple of the complexities are:
1) An @xml:base attribute declared on an entry might be relative to
the original feed's URI, or to @xml:base attributes on parent
elements. These need to be resolved before they can be copied across
into a second feed.
2) The source feed will have atom:entry as a child of atom:feed, but
the second feed will have atom:source as a child of atom:entry. This
switch in the hierarchy means that if the source feed contains an
@xml:lang tag on its entry, but not on its feed, you need to undeclare
@xml:lang on atom:source. Likewise, any @xml:base on atom:entry need
to be resolved because it can no longer be relative to the base of the
atom:feed element.
Eg:
<atom:feed>
<atom:title>Source feed</atom:title>
...
<atom:entry xml:lang="de">
<atom:title>Guten Tag</atom:title>
...
</atom:entry>
<atom:feed>
needs to be embedded as:
<atom:feed>
<atom:title>Second feed</atom:title>
...
<atom:entry xml:lang="de">
<atom:source xml:lang="">
<atom:title>Source feed</atom:title>
...
</atom:source>
<atom:title>Guten Tag</atom:title>
...
</atom:entry>
<atom:feed>
--
Dave
