Binding : Do I need a nodeset?

[Adam Flinton-3]

Dear All,

I have a couple of groups one for editing (i.e. uses input fields) & one
for readonly (ie only uses output fields).

Which to show is determined by binding to a bind which has a "relevant"
attrib set e.g.

       <xforms:bind id="OID_EDIT"
relevant="instance('OIDVals')//oids[1]/@active = 0 and
instance('systemInformation')//@nodeEditable[1] = 1"
nodeset="instance('systemInformation')//@localEdit[1]"/>
        <xforms:bind id="OID_NO_EDIT"
relevant="instance('OIDVals')//oids[1]/@active = 1 and
instance('systemInformation')//@nodeEditable[1] = 1"
nodeset="instance('systemInformation')//@localNoEdit[1]"/>

& then:

<xforms:group appearance="minimal" bind="OID_EDIT" id="OID_Group_Editable">

etc.

I can only seem to get it to work (in Chiba) is via having a nodeset
which is just there to bind to. I.e. I create 2 dummy/empty attributes
within an instance & use them as the nodeset reference.

Do I need a nodeset ?

e.g. should

     <xforms:bind id="OID_EDIT"
relevant="instance('OIDVals')//oids[1]/@active = 0 and
instance('systemInformation')//@nodeEditable[1] = 1" />
     <xforms:bind id="OID_NO_EDIT"
relevant="instance('OIDVals')//oids[1]/@active = 1 and
instance('systemInformation')//@nodeEditable[1] = 1" />

Work in the same way?

It appears to work for calculated values e.g.

<xforms:bind id="CountOv" calculate="count(instance('OIDVals')//ov)"/>

So are there any rules wrt binding & when you need a nodeset & when you
don't?

TIA

Adam

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[Mark Birbeck-4]

Hi Adam,

You always need a nodeset, even with @calculate. I'm surprised that
you are getting Chiba to output something using @calculate with no
@nodeset value, so you might want to double-check that you really are
seeing what you think you are seeing.

One way to understand xf:bind is to see it as adding extra
'properties' to an instance node. I realise that in your particular
example you want to have relevance based only on the result of an
expression, but that's not possible; in XForms you have to make some
existing node relevant, based on the expression you want. And if no
obvious node exists, then unfortunately, as you have discovered, you
usually need to invent one.

So the minimum you will need is this:

  <xf:bind
   nodeset="instance('systemInformation')//@localEdit[1]"
   relevant="
    instance('OIDVals')//oids[1]/@active = 0
     and
    instance('systemInformation')//@nodeEditable[1] = 1
   "
  />

The reason I say "minimum" is that I haven't added an @id value here.
You only need the @id value if you want a shorthand for the node
referred to by @nodeset. If all you want is the relevance mechanism
itself, you can do this:

  <xf:group ref="instance('systemInformation')//@localEdit[1]">
    ...
  </xf:group>

I mention this only to draw attention to the two roles that xf:bind
plays -- one to give a 'name' to a nodeset, and the other to add extra
'properties' to each node in that nodeset.

Of course, in your example it's a good idea to use the named binding
feature too, so that you don't need to worry about keeping the two
XPath expressions in sync:

  <xf:bind
   id="bnd-oid-edit"
   nodeset="instance('systemInformation')//@localEdit[1]"
   relevant="
    instance('OIDVals')//oids[1]/@active = 0
     and
    instance('systemInformation')//@nodeEditable[1] = 1
   "
  />

  <xf:group bind="bnd-oid-edit">
    ...
  </xf:group>

If you're wondering about the "bnd-oid-edit" ID value, by the way,
it's because over the years we've discovered that a little Hungarian
notation can go a long way to helping keep the numerous @id values
that you need in XForms, distinct.

It's also worth pointing out -- and I hope I'm not telling grandmother
to suck eggs here :) -- that "//" usually causes quite a performance
hit in XSLT/XPath engines, so it's often worth spelling out the full
XPath for your instance data. (Especially if you are mapping that
XPath to a named nodeset, via xf:bind.)

Regards,

Mark

On Thu, Aug 6, 2009 at 1:58 PM, Adam Flinton<adam.flinton@...> wrote:

> Dear All,
>
> I have a couple of groups one for editing (i.e. uses input fields) & one
> for readonly (ie only uses output fields).
>
> Which to show is determined by binding to a bind which has a "relevant"
> attrib set e.g.
>
>      <xforms:bind id="OID_EDIT"
> relevant="instance('OIDVals')//oids[1]/@active = 0 and
> instance('systemInformation')//@nodeEditable[1] = 1"
> nodeset="instance('systemInformation')//@localEdit[1]"/>
>       <xforms:bind id="OID_NO_EDIT"
> relevant="instance('OIDVals')//oids[1]/@active = 1 and
> instance('systemInformation')//@nodeEditable[1] = 1"
> nodeset="instance('systemInformation')//@localNoEdit[1]"/>
>
> & then:
>
> <xforms:group appearance="minimal" bind="OID_EDIT" id="OID_Group_Editable">
>
> etc.
>
> I can only seem to get it to work (in Chiba) is via having a nodeset
> which is just there to bind to. I.e. I create 2 dummy/empty attributes
> within an instance & use them as the nodeset reference.
>
> Do I need a nodeset ?
>
> e.g. should
>
>    <xforms:bind id="OID_EDIT"
> relevant="instance('OIDVals')//oids[1]/@active = 0 and
> instance('systemInformation')//@nodeEditable[1] = 1" />
>    <xforms:bind id="OID_NO_EDIT"
> relevant="instance('OIDVals')//oids[1]/@active = 1 and
> instance('systemInformation')//@nodeEditable[1] = 1" />
>
> Work in the same way?
>
> It appears to work for calculated values e.g.
>
> <xforms:bind id="CountOv" calculate="count(instance('OIDVals')//ov)"/>
>
> So are there any rules wrt binding & when you need a nodeset & when you
> don't?
>
> TIA
>
> Adam
>
> ********************************************************************************************************************
>
> This message may contain confidential information. If you are not the
> intended recipient please inform the
> sender that you have received the message in error before deleting it.
> Please do not disclose, copy or distribute information in this e-mail or
> take any action in reliance on its contents:
> to do so is strictly prohibited and may be unlawful.
>
> Thank you for your co-operation.
>
> NHSmail is the secure email and directory service available for all NHS
> staff in England and Scotland
> NHSmail is approved for exchanging patient data and other sensitive
> information with NHSmail and GSI recipients
> NHSmail provides an email address for your career in the NHS and can be
> accessed anywhere
> For more information and to find out how you can switch, visit
> www.connectingforhealth.nhs.uk/nhsmail
>
> ********************************************************************************************************************
>
>
>

--
Mark Birbeck, webBackplane

mark.birbeck@...

http://webBackplane.com/mark-birbeck

webBackplane is a trading name of Backplane Ltd. (company number
05972288, registered office: 2nd Floor, 69/85 Tabernacle Street,
London, EC2A 4RR)

[Adam Flinton-3]

Mark Birbeck wrote:

> Hi Adam,
>
> You always need a nodeset, even with @calculate. I'm surprised that
> you are getting Chiba to output something using @calculate with no
> @nodeset value, so you might want to double-check that you really are
> seeing what you think you are seeing.
>
> One way to understand xf:bind is to see it as adding extra
> 'properties' to an instance node. I realise that in your particular
> example you want to have relevance based only on the result of an
> expression, but that's not possible; in XForms you have to make some
> existing node relevant, based on the expression you want. And if no
> obvious node exists, then unfortunately, as you have discovered, you
> usually need to invent one.
>

That is what I was thinking.....

I wonder if there is scope within any improvements to XForms to have a
<xforms:variable/> element

Much as with XSLT or similar......

The normal use cases are wrt checking values e.g. my "check unique" check:

        <xforms:bind
            calculate="if(instance('OIDVals')/oids/@active = 1,true(),if
(count(instance('OIDVals')//ov[@full = instance('main')/@full]) <=
instance('OIDVals')//oids[1]/@exist,true(),false()))"
            id="unique_OID" nodeset="instance('uniqueOID')/@val"/>

Or as stated in the previous post wrt displaying one group vs another.

Adam

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to do so is strictly prohibited and may be unlawful.

Thank you for your co-operation.

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NHSmail is approved for exchanging patient data and other sensitive information with NHSmail and GSI recipients
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[Mark Birbeck-4]

HI Adam,

> I wonder if there is scope within any improvements to XForms to have a
> <xforms:variable/> element
>
> Much as with XSLT or similar......

It's been discussed many times over the years, and I'm sure it will happen.


> The normal use cases are wrt checking values e.g. my "check unique" check:
>
>       <xforms:bind
>           calculate="if(instance('OIDVals')/oids/@active = 1,true(),if
> (count(instance('OIDVals')//ov[@full = instance('main')/@full]) <=
> instance('OIDVals')//oids[1]/@exist,true(),false()))"
>           id="unique_OID" nodeset="instance('uniqueOID')/@val"/>
>
> Or as stated in the previous post wrt displaying one group vs another.

If you have multiple groups, and multiple possible values (obtained
via @calculate) then you could use a clever little trick that I first
saw used by David Landwehr.

The idea is to bind multiple groups to the same node (in your case it
might be @val), but to then add an XPath filter with the expression
you want relevance to be based on:

  <xf:group ref="instance('uniqueOID')">
    <xf:group ref="@val[. = 1]">
      ...
    </xf:group>

    <xf:group ref="@val[. = 2]">
      ...
    </xf:group>

    <xf:group ref="@val[. = 3]">
      ...
    </xf:group>
  </xf:group>

This has the effect of creating an empty nodeset for each @ref that
contains a filter that evaluates to false. The default behaviour in
XForms, for a binding to a node that doesn't exist, is to act as if
the binding is to a non-relevant node.

In short, you should only ever get a maximum of one of these groups
being relevant at any one time, and with this approach there is no
need to use xf:bind, other than for the calculation to set the
selection criteria.

Regards,

Mark

--
Mark Birbeck, webBackplane

mark.birbeck@...

http://webBackplane.com/mark-birbeck

webBackplane is a trading name of Backplane Ltd. (company number
05972288, registered office: 2nd Floor, 69/85 Tabernacle Street,
London, EC2A 4RR)

[John Boyer]

Just to clarify for archival purposes, when Mark said you always need a bind nodeset even for calculate, that's not exactly true.  You always need to have a node to which you are attaching the model item property, which is what Mark is explaining.

The nodeset binding on xf:bind is optional, but if you leave it off, then the other bind attributes are evaluated according to the inscope evaluation context.  This is handy when you are using inner binds.  So, for example, you can say

<xf:bind nodeset="some/common/node">
   <xf:bind relevant="some expression"/>
   <xf:bind nodeset="some child" calculate="some expression"/>
</xf:bind>

Notice that the inner bind with the relevant attribute has no nodeset attribute.

If you have an outermost bind with no nodeset, then the model item property is being attached to the default node, which is the root element of the default instance.  

Also, if you define the same model item property more than once for a given node, the processor is supposed to quit with an exception.   When you didn't use nodeset, you were attaching two relevant model item properties to the root element of the default instance, which is why your program wasn't working.  If you had tried to do a second calculate, you would have gotten the same error.

As Mark explained, attributes like relevant and calculate are not applied to the bind itself, which is what I believe you were thinking.  Instead, the bind *binds* those properties to data nodes.  Then, your UI controls use "single node bindings" (e.g. ref) to refer to the same nodes in order to get at their value (whether or not calculated) and their other model item properties (like relevant).

Cheers,
John M. Boyer, Ph.D.
STSM, Interactive Documents and Web 2.0 Applications
Chair, W3C Forms Working Group
Workplace, Portal and Collaboration Software
IBM Victoria Software Lab
E-Mail: boyerj@...  

Blog: http://www.ibm.com/developerworks/blogs/page/JohnBoyer
Blog RSS feed: http://www.ibm.com/developerworks/blogs/rss/JohnBoyer?flavor=rssdw

From:	Mark Birbeck <mark.birbeck@...>
To:	adam.flinton@...
Cc:	"www-forms@..." <www-forms@...>
Date:	08/06/2009 05:50 AM
Subject:	Re: Binding : Do I need a nodeset?

---

Hi Adam,

You always need a nodeset, even with @calculate. I'm surprised that
you are getting Chiba to output something using @calculate with no
@nodeset value, so you might want to double-check that you really are
seeing what you think you are seeing.

One way to understand xf:bind is to see it as adding extra
'properties' to an instance node. I realise that in your particular
example you want to have relevance based only on the result of an
expression, but that's not possible; in XForms you have to make some
existing node relevant, based on the expression you want. And if no
obvious node exists, then unfortunately, as you have discovered, you
usually need to invent one.

So the minimum you will need is this:

 <xf:bind
  nodeset="instance('systemInformation')//@localEdit[1]"
  relevant="
   instance('OIDVals')//oids[1]/@active = 0
    and
   instance('systemInformation')//@nodeEditable[1] = 1
  "
 />

The reason I say "minimum" is that I haven't added an @id value here.
You only need the @id value if you want a shorthand for the node
referred to by @nodeset. If all you want is the relevance mechanism
itself, you can do this:

 <xf:group ref="instance('systemInformation')//@localEdit[1]">
   ...
 </xf:group>

I mention this only to draw attention to the two roles that xf:bind
plays -- one to give a 'name' to a nodeset, and the other to add extra
'properties' to each node in that nodeset.

Of course, in your example it's a good idea to use the named binding
feature too, so that you don't need to worry about keeping the two
XPath expressions in sync:

 <xf:bind
  id="bnd-oid-edit"
  nodeset="instance('systemInformation')//@localEdit[1]"
  relevant="
   instance('OIDVals')//oids[1]/@active = 0
    and
   instance('systemInformation')//@nodeEditable[1] = 1
  "
 />

 <xf:group bind="bnd-oid-edit">
   ...
 </xf:group>

If you're wondering about the "bnd-oid-edit" ID value, by the way,
it's because over the years we've discovered that a little Hungarian
notation can go a long way to helping keep the numerous @id values
that you need in XForms, distinct.

It's also worth pointing out -- and I hope I'm not telling grandmother
to suck eggs here :) -- that "//" usually causes quite a performance
hit in XSLT/XPath engines, so it's often worth spelling out the full
XPath for your instance data. (Especially if you are mapping that
XPath to a named nodeset, via xf:bind.)

Regards,

Mark

On Thu, Aug 6, 2009 at 1:58 PM, Adam Flinton<adam.flinton@...> wrote:
> Dear All,
>
> I have a couple of groups one for editing (i.e. uses input fields) & one
> for readonly (ie only uses output fields).
>
> Which to show is determined by binding to a bind which has a "relevant"
> attrib set e.g.
>
>      <xforms:bind id="OID_EDIT"
> relevant="instance('OIDVals')//oids[1]/@active = 0 and
> instance('systemInformation')//@nodeEditable[1] = 1"
> nodeset="instance('systemInformation')//@localEdit[1]"/>
>       <xforms:bind id="OID_NO_EDIT"
> relevant="instance('OIDVals')//oids[1]/@active = 1 and
> instance('systemInformation')//@nodeEditable[1] = 1"
> nodeset="instance('systemInformation')//@localNoEdit[1]"/>
>
> & then:
>
> <xforms:group appearance="minimal" bind="OID_EDIT" id="OID_Group_Editable">
>
> etc.
>
> I can only seem to get it to work (in Chiba) is via having a nodeset
> which is just there to bind to. I.e. I create 2 dummy/empty attributes
> within an instance & use them as the nodeset reference.
>
> Do I need a nodeset ?
>
> e.g. should
>
>    <xforms:bind id="OID_EDIT"
> relevant="instance('OIDVals')//oids[1]/@active = 0 and
> instance('systemInformation')//@nodeEditable[1] = 1" />
>    <xforms:bind id="OID_NO_EDIT"
> relevant="instance('OIDVals')//oids[1]/@active = 1 and
> instance('systemInformation')//@nodeEditable[1] = 1" />
>
> Work in the same way?
>
> It appears to work for calculated values e.g.
>
> <xforms:bind id="CountOv" calculate="count(instance('OIDVals')//ov)"/>
>
> So are there any rules wrt binding & when you need a nodeset & when you
> don't?
>
> TIA
>
> Adam
>
> ********************************************************************************************************************
>
> This message may contain confidential information. If you are not the
> intended recipient please inform the
> sender that you have received the message in error before deleting it.
> Please do not disclose, copy or distribute information in this e-mail or
> take any action in reliance on its contents:
> to do so is strictly prohibited and may be unlawful.
>
> Thank you for your co-operation.
>
> NHSmail is the secure email and directory service available for all NHS
> staff in England and Scotland
> NHSmail is approved for exchanging patient data and other sensitive
> information with NHSmail and GSI recipients
> NHSmail provides an email address for your career in the NHS and can be
> accessed anywhere
> For more information and to find out how you can switch, visit
> www.connectingforhealth.nhs.uk/nhsmail
>
> ********************************************************************************************************************
>
>
>



--
Mark Birbeck, webBackplane

mark.birbeck@...

http://webBackplane.com/mark-birbeck

webBackplane is a trading name of Backplane Ltd. (company number
05972288, registered office: 2nd Floor, 69/85 Tabernacle Street,
London, EC2A 4RR)

[Mark Birbeck-4]

Hi John,

I was careful to say "you always need a nodeset" rather than "you
always need @nodeset" for exactly the reasons that you said -- that
@nodeset is optional. I was just trying to emphasise that you need to
bind to something, and I thought I'd confuse the issue if I mentioned
nested binds.

However, I forgot all about the evaluation context for a top-level
bind being the first instance/node of the containing model, and that,
as you rightly point out, explains why Chiba was giving Adam some
results when he had @calculate with no @nodeset.

So it seems I couldn't get away with not mentioning nested binds after all. :)

Thanks for the much-needed clarification!

Regards,

Mark

On Thu, Aug 6, 2009 at 4:27 PM, John Boyer<boyerj@...> wrote:

>
> Just to clarify for archival purposes, when Mark said you always need a bind
> nodeset even for calculate, that's not exactly true.  You always need to
> have a node to which you are attaching the model item property, which is
> what Mark is explaining.
>
> The nodeset binding on xf:bind is optional, but if you leave it off, then
> the other bind attributes are evaluated according to the inscope evaluation
> context.  This is handy when you are using inner binds.  So, for example,
> you can say
>
> <xf:bind nodeset="some/common/node">
>    <xf:bind relevant="some expression"/>
>    <xf:bind nodeset="some child" calculate="some expression"/>
> </xf:bind>
>
> Notice that the inner bind with the relevant attribute has no nodeset
> attribute.
>
> If you have an outermost bind with no nodeset, then the model item property
> is being attached to the default node, which is the root element of the
> default instance.
>
> Also, if you define the same model item property more than once for a given
> node, the processor is supposed to quit with an exception.   When you didn't
> use nodeset, you were attaching two relevant model item properties to the
> root element of the default instance, which is why your program wasn't
> working.  If you had tried to do a second calculate, you would have gotten
> the same error.
>
> As Mark explained, attributes like relevant and calculate are not applied to
> the bind itself, which is what I believe you were thinking.  Instead, the
> bind *binds* those properties to data nodes.  Then, your UI controls use
> "single node bindings" (e.g. ref) to refer to the same nodes in order to get
> at their value (whether or not calculated) and their other model item
> properties (like relevant).
>
> Cheers,
> John M. Boyer, Ph.D.
> STSM, Interactive Documents and Web 2.0 Applications
> Chair, W3C Forms Working Group
> Workplace, Portal and Collaboration Software
> IBM Victoria Software Lab
> E-Mail: boyerj@...
>
> Blog: http://www.ibm.com/developerworks/blogs/page/JohnBoyer
> Blog RSS feed:
> http://www.ibm.com/developerworks/blogs/rss/JohnBoyer?flavor=rssdw
>
>
>
>
> From: Mark Birbeck <mark.birbeck@...>
> To: adam.flinton@...
> Cc: "www-forms@..." <www-forms@...>
> Date: 08/06/2009 05:50 AM
> Subject: Re: Binding : Do I need a nodeset?
> ________________________________
>
>
> Hi Adam,
>
> You always need a nodeset, even with @calculate. I'm surprised that
> you are getting Chiba to output something using @calculate with no
> @nodeset value, so you might want to double-check that you really are
> seeing what you think you are seeing.
>
> One way to understand xf:bind is to see it as adding extra
> 'properties' to an instance node. I realise that in your particular
> example you want to have relevance based only on the result of an
> expression, but that's not possible; in XForms you have to make some
> existing node relevant, based on the expression you want. And if no
> obvious node exists, then unfortunately, as you have discovered, you
> usually need to invent one.
>
> So the minimum you will need is this:
>
>  <xf:bind
>   nodeset="instance('systemInformation')//@localEdit[1]"
>   relevant="
>    instance('OIDVals')//oids[1]/@active = 0
>     and
>    instance('systemInformation')//@nodeEditable[1] = 1
>   "
>  />
>
> The reason I say "minimum" is that I haven't added an @id value here.
> You only need the @id value if you want a shorthand for the node
> referred to by @nodeset. If all you want is the relevance mechanism
> itself, you can do this:
>
>  <xf:group ref="instance('systemInformation')//@localEdit[1]">
>    ...
>  </xf:group>
>
> I mention this only to draw attention to the two roles that xf:bind
> plays -- one to give a 'name' to a nodeset, and the other to add extra
> 'properties' to each node in that nodeset.
>
> Of course, in your example it's a good idea to use the named binding
> feature too, so that you don't need to worry about keeping the two
> XPath expressions in sync:
>
>  <xf:bind
>   id="bnd-oid-edit"
>   nodeset="instance('systemInformation')//@localEdit[1]"
>   relevant="
>    instance('OIDVals')//oids[1]/@active = 0
>     and
>    instance('systemInformation')//@nodeEditable[1] = 1
>   "
>  />
>
>  <xf:group bind="bnd-oid-edit">
>    ...
>  </xf:group>
>
> If you're wondering about the "bnd-oid-edit" ID value, by the way,
> it's because over the years we've discovered that a little Hungarian
> notation can go a long way to helping keep the numerous @id values
> that you need in XForms, distinct.
>
> It's also worth pointing out -- and I hope I'm not telling grandmother
> to suck eggs here :) -- that "//" usually causes quite a performance
> hit in XSLT/XPath engines, so it's often worth spelling out the full
> XPath for your instance data. (Especially if you are mapping that
> XPath to a named nodeset, via xf:bind.)
>
> Regards,
>
> Mark
>
> On Thu, Aug 6, 2009 at 1:58 PM, Adam Flinton<adam.flinton@...> wrote:
>> Dear All,
>>
>> I have a couple of groups one for editing (i.e. uses input fields) & one
>> for readonly (ie only uses output fields).
>>
>> Which to show is determined by binding to a bind which has a "relevant"
>> attrib set e.g.
>>
>>      <xforms:bind id="OID_EDIT"
>> relevant="instance('OIDVals')//oids[1]/@active = 0 and
>> instance('systemInformation')//@nodeEditable[1] = 1"
>> nodeset="instance('systemInformation')//@localEdit[1]"/>
>>       <xforms:bind id="OID_NO_EDIT"
>> relevant="instance('OIDVals')//oids[1]/@active = 1 and
>> instance('systemInformation')//@nodeEditable[1] = 1"
>> nodeset="instance('systemInformation')//@localNoEdit[1]"/>
>>
>> & then:
>>
>> <xforms:group appearance="minimal" bind="OID_EDIT"
>> id="OID_Group_Editable">
>>
>> etc.
>>
>> I can only seem to get it to work (in Chiba) is via having a nodeset
>> which is just there to bind to. I.e. I create 2 dummy/empty attributes
>> within an instance & use them as the nodeset reference.
>>
>> Do I need a nodeset ?
>>
>> e.g. should
>>
>>    <xforms:bind id="OID_EDIT"
>> relevant="instance('OIDVals')//oids[1]/@active = 0 and
>> instance('systemInformation')//@nodeEditable[1] = 1" />
>>    <xforms:bind id="OID_NO_EDIT"
>> relevant="instance('OIDVals')//oids[1]/@active = 1 and
>> instance('systemInformation')//@nodeEditable[1] = 1" />
>>
>> Work in the same way?
>>
>> It appears to work for calculated values e.g.
>>
>> <xforms:bind id="CountOv" calculate="count(instance('OIDVals')//ov)"/>
>>
>> So are there any rules wrt binding & when you need a nodeset & when you
>> don't?
>>
>> TIA
>>
>> Adam
>>
>>
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>
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>
> --
> Mark Birbeck, webBackplane
>
> mark.birbeck@...
>
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--
Mark Birbeck, webBackplane

mark.birbeck@...

http://webBackplane.com/mark-birbeck

webBackplane is a trading name of Backplane Ltd. (company number
05972288, registered office: 2nd Floor, 69/85 Tabernacle Street,
London, EC2A 4RR)

[Alessandro Vernet]

Adam,

Adam Flinton-3 wrote:

I wonder if there is scope within any improvements to XForms to have a
<xforms:variable/> element

Much as with XSLT or similar......

There is hope! This is something that is being discussed [1] and supported as already supported today as a non-standard extension by some implementation, e.g. [2].

Alex

[1] http://www.w3.org/MarkUp/Forms/wiki/Variables_in_XPath
[2] http://www.orbeon.com/ops/doc/reference-xforms-extensions#variables

[Adam Flinton-3]

Alessandro Vernet wrote:

> Adam,
>
>
> Adam Flinton-3 wrote:
>
>> I wonder if there is scope within any improvements to XForms to have a
>> <xforms:variable/> element
>>
>> Much as with XSLT or similar......
>>
>>
>
> There is hope! This is something that is being discussed [1] and supported
> as already supported today as a non-standard extension by some
> implementation, e.g. [2].
>
> Alex
>
> [1] http://www.w3.org/MarkUp/Forms/wiki/Variables_in_XPath
> [2] http://www.orbeon.com/ops/doc/reference-xforms-extensions#variables
>
> -----
>

Hurrah.

Things like "read/write", "editable/not editable", "isUnique" are fairly
well established as variable use case.

Adam

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