No, there is no choice left to the
adopter. You just need to read a slightly larger section of the Architecture
Spec. This section is just making the point that no matter what the source of
the values is, that it is never additive as far as conref is concerned.
-Jeff
From: Bruce Nevin
(bnevin) [mailto:]
Sent: Thursday, April 16, 2009
4:24 PM
To: dita
Subject: RE: [dita] Inheritance of
attributes through mapref
I'm
trying to understand this:
“A given
attribute value on the resolved element comes in its entirety from either the
source or target: the attribute values of the target and source for a given
attribute are never additive, even if the property (such as the audience type)
takes a list of values.”
The spec
seems to leave that up to the adopter. Should it at least advise to pick one
and stick to it?
I suppose
there's a case where you want the attribute in the target to be determinative.
Here's one where I think the source clearly should be
determinative.
Source in
thistopic.dita:
<p
conref="thattopic.dita#topicid/elementidX"
audience="beginner"/>
Target in
thattopic.dita:
<concept
id="topicid">
...
<p
id="elementidX" audience="expert">Expert
stuff.</p>
...
</concept>
(This
also illustrates why they shouldn't be additive.)
Should
the advice be that it is more manageable never to put profiling attributes in
the target and always have them instead on the conref-bearing source elements?
For example:
Source in
thistopic.dita:
<p
conref="thattopic.dita#topicid/elementidX"
audience="beginner"/>
<p
conref="thattopic.dita#topicid/elementidY"
audience="expert"/>
Target in
thattopic.dita:
<concept
id="topicid">
...
<p
id="elementidX" audience="expert">Beginner
stuff.</p>
<p
id="elementidY" audience="expert">Expert
stuff.</p>
...
</concept>
User
would have to be able to inspect the attribute values in the target so as to
pick the right one for each conref. But you have to pick the right target for
the conref in every case anyway.
/Bruce
From: Su-Laine
Yeo [mailto:]
Sent: Thursday, April 16, 2009
2:42 PM
To: dita
Subject: RE: [dita] Inheritance of
attributes through mapref
That makes sense to
me Jeff. I agree that changing the spec in this regard would be a big change
and that we’ll probably have to not change course for 1.2.
I’ve thought a
bit more about conditional processing with respect to other mechanisms for
including child document sets in parent document sets. I can see more bad news,
unfortunately. The use cases I’ve described are examples of a general
case in which a child document set contains a mixture of conditional and
unconditional content, that within a parent document set should be treated as
entirely conditional. The Architectural Spec rules for conref attributes
don’t handle this case well either:
“A given
attribute value on the resolved element comes in its entirety from either the
source or target: the attribute values of the target and source for a given
attribute are never additive, even if the property (such as the audience type)
takes a list of values.”
This rule will give
undesired results if the conref target contains a mixture of conditional and
unconditional content and the unconditional content should be treated as
conditional in the context of the source document. So this rule is one more
thing to think about changing.
Su-Laine
From: Ogden, Jeff
[mailto:]
Sent: Wednesday, April 15, 2009
7:11 PM
To: Su-Laine Yeo; dita
Subject: RE: [dita] Inheritance of
attributes through mapref
I went back to the DITA 1.0 specification
to see what that said about map to topic cascading. What I found is
almost identical to the version in the DITA 1.1 spec.:
Topic properties in topics and maps
The properties of a topic
can be specified in the topic itself or on references to the topic within maps.
. . .
If a property is set in
both the map and topic, the map properties are additive if the property (such
as the
audience type) takes a list
of values. If, instead, the property (such as the importance) takes a single
value, the map property
overrides the topic property.
Here is the section from the DITA 1.1
spec. for comparison:
Topic properties in topics and maps
The properties of a topic
(including metadata attributes and metadata elements) can be specified in the
topic itself or in
references to the topic within maps.
. . .
If a property is set in
both the map and topic, the map properties are additive if the property (such
as the
audience type) takes a list
of values. If, instead, the property (such as the importance) takes a single
value, the map property overrides
the topic property.
Given this I think it is hard to argue
that the DITA specifications are “wrong”. I think a case
could be made that the specification should be changed. But such a change
should really require a full-blown proposal, review, and a vote. And I think
that that would need to wait for DITA 1.3. And it might need to wait for DITA
2.0 since it is an incompatible change that would change the behavior for
existing documents that conform to the DITA 1.0 and 1.1 specifications as originally
written and approved.
My own not too well thought out feeling is
that we should try to avoid an incompatible change here altogether by coming up
with a syntax that allows authors to explicitly say which behavior they want
(override, merge, provide new default values for those cases where no value has
been explicitly given, …). But that will take some care to design
and so it too would need to wait for DITA 1.3 or 2.0.
-Jeff
From: Su-Laine Yeo
[mailto:]
Sent: Wednesday, April 15, 2009
8:35 PM
To: dita
Subject: RE: [dita] Inheritance of
attributes through mapref
Hi Jeff,
Thanks for providing
the relevant section of the 1.1 spec. I think the TC should re-examine whether
the spec might be wrong. I agree that this thread didn’t start out with
the intention of revisiting the 1.1 map-to-topic cascading rules, but if
they’re wrong we should fix them before copying the problem over to the
map-to-map cascading rules.
Having said that, I
thought more about the example I gave, and I think the conclusion I first
reached is not quite right either. If there is a difference between the
conditional values on a topicref and the values on an element in the referenced
topic, the processor should have different rules depending on whether the
element has values for that attribute or not. In the example, if topic 3
contains an element with no “audience” attribute, that element
should be processed as if it inherits audience values from the topicref.
However, if topic 3 contains an element with an “audience”
attribute, that element should be processed as if its audience values are the
intersection between the local values and any audience values on the topicref.
When I think about
this issue abstractly, it also seems logicially wrong to ask processors to add
conditional attribute values that are set at different levels. The way that
conditional attributes work is that when you specify what audiences an element
is for, you are implicitly saying that it is not for any other audience. E.g.
when you say that audience = “c”, you are saying that the audience
is not B or A.
Here is a second use
case, which is an extension of the first but illuminates a few more issues: You
are creating a document for three audiences, A, B, and C. The map includes:
1) a topic that is
common to all audiences
2) a topic in which
the entire topic is for audience A only
3) a topic that does
not apply to A at all, and contains some elements that apply only to B and some
elements that apply only to C
4) a topicref
pointing to a submap that includes the following topics:
- 4.1) a topic that
applies to B and C only
- 4.2) a topic for B
only
- 4.3) a topic that
contains some elements that apply only to B and some elements that apply only
to C
If generating output
for audience A, you will want to include topic 1 and 2. Topic 3 and submap 4
should not appear.
If generating output
for audience B, you will want the TOC to include topic 1, unconditional and
B-only elements from topic 3, topic 4.1, topic 4.2, and unconditional and
B-only elements from topic 4.3.
There are four ways
to indicate that topic 4.1 applies to B and C only:
- mark topicref 4.1
as having audience =”b c”
- mark topic 4.1 as
having audience =”b c”
- mark submap 4 as
having audience =”b c”
- mark topicref 4 as
having audience =”b c”. This is useful because it is possible that
the author of submap 4 knew that audiences B and C existed, but was unaware of
the existence of audience A, and so did not indicate anywhere within the submap
or its topics that 4.1 was a conditional topic. In this case, the author of the
parent map should set “audience=”b c” on the topicref that
points to submap 4.
Using any of these
four methods, the processor will give desired results if it follows the
following rules for both map-to-topic and map-to-map cascading:
- An element
inherits conditional attribute values if it has no local values for that
attribute.
- An element is
processed as if it has the intersection of local and inherited attribute
values, if any local values exist for that attribute.
That’s all my
brain can handle today :)
Best,
Su-Laine
Su-Laine Yeo
Interaction Design Specialist
JustSystems
Canada, Inc.
Office: 778-327-6356
www.justsystems.com
From: Ogden, Jeff
[mailto:]
Sent: Wednesday, April 15, 2009
1:55 PM
To: dita
Subject: RE: [dita] Inheritance of
attributes through mapref
Su-Laine, thanks for providing a concrete
use case.
Is the use case just a single map and
cascading of attribute properties from that map to the topics? It isn’t
talking about map to map cascading is it?
I thought that the map to topic case was
already settled in the DITA 1.1 specification and we were just talking about
cascading in the map to map case. Am I mistaken about that?
Here is what the section “Topic
properties in topics and maps” in the DITA 1.1 Architecture Spec. says:
The properties of a topic
(including metadata attributes and metadata elements) can be specified in the
topic itself or in
references to the topic within maps.
. . .
If a property is set in
both the map and topic, the map properties are additive if the property (such
as the
audience type) takes a list
of values. If, instead, the property (such as the importance) takes a single
value, the map property
overrides the topic property.
And I’m arguing that for
simplicity’s sake we should follow the same rules for the map to map case
as already exist for the map to topic case.
-Jeff
From: Su-Laine Yeo
[mailto:]
Sent: Tuesday, April 14, 2009 2:45
PM
To: dita
Subject: RE: [dita] Inheritance of
attributes through mapref
Regarding merging
vs. overriding for conditional attributes, let’s consider the following
example: You are creating a document for three audiences, A, B, and C. The map
includes:
1) a topic that is
common to all audiences
2) a topic in which
the entire topic is for audience A only
3) a topic which
does not apply to A at all, and contains some elements that apply only to B and
some elements that apply only to C
If generating output
for audience A, you will want to include topic 1 and 2. Topic 3 should not
appear at all, not even in the TOC.
If generating output
for audience B, you will want the TOC to include topic 1 and topic 3. Topic 3
should include any unconditional elements, include the elements that apply to
B, and exclude the elements that apply only to C.
Currently the OT
gives the desired behaviour if you set audience=”a” on the topicref
to topic 2 and audience=”b c” on the topicref to topic 3. If we
were to say that audience attribute values on a topicref are added to the
conditional attributes within the target topic, you would not get the desired
behaviour in this case, because when generating output for audience B, you
would get all the content for audience C in topic 3. I have thought of trying
to get the desired behaviour by explicitly conditionalizing all of the elements
in topic 3 instead of putting conditions on the topicref, however this is not
feasible because you cannot conditionalize element types such as <title>.
So I think this
particular example supports a rule that conditional attribute values should be
processed as the intersection as of the values on the topicref and the values
on the further down the hierarchy. I think this is the rule which is actually
implemented in the current OT.
Regards,
Su-Laine
Su-Laine Yeo
Interaction Design Specialist
JustSystems
Canada, Inc.
Office: 778-327-6356
www.justsystems.com
> The two open questions are:
> 1) What about attributes like @audience, which take multiple
values? If my
> map reference has audience="a b", and the map has
audience="c", does "a b"
> override "c", or does this result in "a b c"?
If the latter, we will need
> to come up with an authoritative list of which attributes act this
way (as
> opposed to the override behavior of @toc and @linking).
Don’t we already have a list for the
later case (merge)? If an attribute value cascades and the attribute
allows multiple values then. it merges. If an attribute value cascades
and the attribute does not allow multiple values. it overrides.
My goal here is just to make the rules for
map to map cascading as much like the rules for other cascading as possible
because that is more consistent and therefore easier to remember. And
while the DITA 1.1 spec. didn’t talk about map to map cascading
explicitly, when it did talk about cascading more generally it talked about
merging multi-valued attributes and overriding single values attributes. So it
just seem unnec3essairly complicated to introduce a new case. Note too
that this question is about general cascading and that there are separate rules
for conref behavior.
