xml and lua again

xml and lua again

[Thomas A. Schmitz]

Hi all,

again, I'm playing a bit with processing my xml in lua. I want a simple 
interface for processing tables (I don't need all the power and 
complexity of cals tables and want to learn something in the process). 
And I thought that collecting the setups in lua might be the easiest 
way, but so far, I haven't been successful. Here's an example:

\startbuffer[test]
<a>
   <nattable frame="on">
     <tr>
       <td>1</td>
       <td>2</td>
       <td>3</td>
       <td>4</td>
     </tr>
     <tr>
       <td>5</td>
       <td>6</td>
       <td>7</td>
       <td>8</td>
     </tr>
   </nattable>
</a>
\stopbuffer

\startxmlsetups xml:testsetups
	\xmlsetsetup{main}{a|nattable|tr|td|}{xml:*}
\stopxmlsetups

\xmlregistersetup{xml:testsetups}

\startxmlsetups xml:a
	\xmlflush{#1}
\stopxmlsetups

\startxmlsetups xml:nattable
	\startluacode
	  framestate = lxml.att("#1", "frame")
	  context(framestate)
	  context(true)
	  context.placefigure( { "here" }, "none" , function()
	    context.setupTABLE( { "frame=on" } )
	    context.bTABLE()
	     context.xmlflush("#1")
	    context.eTABLE()
	  end)
	\stopluacode
\stopxmlsetups

\startxmlsetups xml:tr
	\startluacode
	  context.bTR()
	    context.xmlflush("#1")
	  context.eTR()
	\stopluacode
\stopxmlsetups

\startxmlsetups xml:td
	\startluacode
	  context.bTD()
	    context.xmlflush("#1")
	  context.eTD()
	\stopluacode
\stopxmlsetups

\starttext
\xmlprocessbuffer{main}{test}{}
\stoptext

question: I have the value "on" in the lua variable "framestate." But 
how can I pass this on to the line
context.setupTABLE( { "frame=on" } )?
I tried something like
context.setupTABLE( { "frame=" .. framestate } )
but that doesn't work. Any suggestions?

Thomas
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___________________________________________________________________________________

Re: xml and lua again

[Peter Rolf]

Hi Thomas,

Am 22.10.2011 18:46, schrieb Thomas A. Schmitz:
> Hi all,
> 
> again, I'm playing a bit with processing my xml in lua. I want a simple
> interface for processing tables (I don't need all the power and
> complexity of cals tables and want to learn something in the process).
> And I thought that collecting the setups in lua might be the easiest
> way, but so far, I haven't been successful. Here's an example:
> 
> \startbuffer[test]
> <a>
>   <nattable frame="on">
>     <tr>
>       <td>1</td>
>       <td>2</td>
>       <td>3</td>
>       <td>4</td>
>     </tr>
>     <tr>
>       <td>5</td>
>       <td>6</td>
>       <td>7</td>
>       <td>8</td>
>     </tr>
>   </nattable>
> </a>
> \stopbuffer
> 
> \startxmlsetups xml:testsetups
>     \xmlsetsetup{main}{a|nattable|tr|td|}{xml:*}
> \stopxmlsetups
> 
> \xmlregistersetup{xml:testsetups}
> 
> \startxmlsetups xml:a
>     \xmlflush{#1}
> \stopxmlsetups
> 
> \startxmlsetups xml:nattable
>     \startluacode
>       framestate = lxml.att("#1", "frame")
>       context(framestate)
>       context(true)
>       context.placefigure( { "here" }, "none" , function()
>         context.setupTABLE( { "frame=on" } )
>         context.bTABLE()
>          context.xmlflush("#1")
>         context.eTABLE()
>       end)
>     \stopluacode
> \stopxmlsetups
> 
> \startxmlsetups xml:tr
>     \startluacode
>       context.bTR()
>         context.xmlflush("#1")
>       context.eTR()
>     \stopluacode
> \stopxmlsetups
> 
> \startxmlsetups xml:td
>     \startluacode
>       context.bTD()
>         context.xmlflush("#1")
>       context.eTD()
>     \stopluacode
> \stopxmlsetups
> 
> \starttext
> \xmlprocessbuffer{main}{test}{}
> \stoptext
> 
> question: I have the value "on" in the lua variable "framestate." But
> how can I pass this on to the line
> context.setupTABLE( { "frame=on" } )?
> I tried something like
> context.setupTABLE( { "frame=" .. framestate } )

"frame=" .. tostring(framestate)

seems to work. Anyhow, if you are planning to do some more complex
stuff, you should separate the lua from the tex code.

The advantages are
- no catcode limitations
  Then you can use nice stuff like
  string.format("frame=%s",framestate)
- in case of lua errors you get the real line number
- lua syntax check is possible

Load the lua code at the beginning of your tex file with

\registerctxluafile{filename_without_suffix}{version number or empty}

One last but important tip: if you get lua errors like 'undefined
whatever', check your lua file with 'luatexc -p foo.lua' (lua compiler).
A single syntax error in the lua file and all of its content is ignored!
Can be quite frustrating to find the error cause, if all of your lua
code is undefined right from the beginning.


Best wishes,  Peter


PS: lua programming is most efficient when done in direct moon light,
while drinking a glass of fresh goat milk! Mh, can't find the link to
this interesting statistic right now... so you just have to believe me
and give it a try.. :-)
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___________________________________________________________________________________

Re: xml and lua again

[Thomas A. Schmitz]

Hi Peter,

thanks for your reply, and I'll keep the bit about goat milk in mind :-).


> "frame=" .. tostring(framestate)

It has the advantage of making the example compile. It has the drawback 
of not doing anything :-)

> seems to work. Anyhow, if you are planning to do some more complex
> stuff, you should separate the lua from the tex code.
>
> The advantages are
> - no catcode limitations
>    Then you can use nice stuff like
>    string.format("frame=%s",framestate)
> - in case of lua errors you get the real line number
> - lua syntax check is possible
>
> Load the lua code at the beginning of your tex file with
>
> \registerctxluafile{filename_without_suffix}{version number or empty}
>
> One last but important tip: if you get lua errors like 'undefined
> whatever', check your lua file with 'luatexc -p foo.lua' (lua compiler).
> A single syntax error in the lua file and all of its content is ignored!
> Can be quite frustrating to find the error cause, if all of your lua
> code is undefined right from the beginning.

OK, that sounds like very good advice - I'll see if I can manage to 
apply this for xml style sheets.

Thanks a lot, and best wishes

Thomas
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___________________________________________________________________________________

Re: xml and lua again

[Peter Rolf]

Am 23.10.2011 16:37, schrieb Thomas A. Schmitz:
> Hi Peter,
> 
> thanks for your reply, and I'll keep the bit about goat milk in mind :-).
> 
> 
>> "frame=" .. tostring(framestate)
> 
> It has the advantage of making the example compile. It has the drawback
> of not doing anything :-)
>
(sadly) true :-)

I will look into it. Looks like I need a big glass of goat milk before
(can't wait for the moon)...

>> seems to work. Anyhow, if you are planning to do some more complex
>> stuff, you should separate the lua from the tex code.
>>
>> The advantages are
>> - no catcode limitations
>>    Then you can use nice stuff like
>>    string.format("frame=%s",framestate)
>> - in case of lua errors you get the real line number
>> - lua syntax check is possible
>>
>> Load the lua code at the beginning of your tex file with
>>
>> \registerctxluafile{filename_without_suffix}{version number or empty}
>>
>> One last but important tip: if you get lua errors like 'undefined
>> whatever', check your lua file with 'luatexc -p foo.lua' (lua compiler).
>> A single syntax error in the lua file and all of its content is ignored!
>> Can be quite frustrating to find the error cause, if all of your lua
>> code is undefined right from the beginning.
> 
> OK, that sounds like very good advice - I'll see if I can manage to
> apply this for xml style sheets.
> 
> Thanks a lot, and best wishes
> 
> Thomas
> 

___________________________________________________________________________________
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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________

Re: xml and lua again

[Peter Rolf]

Am 22.10.2011 18:46, schrieb Thomas A. Schmitz:
> Hi all,
> 
> again, I'm playing a bit with processing my xml in lua. I want a simple
> interface for processing tables (I don't need all the power and
> complexity of cals tables and want to learn something in the process).
> And I thought that collecting the setups in lua might be the easiest
> way, but so far, I haven't been successful. Here's an example:
> 
> \startbuffer[test]
> <a>
>   <nattable frame="on">
>     <tr>
>       <td>1</td>
>       <td>2</td>
>       <td>3</td>
>       <td>4</td>
>     </tr>
>     <tr>
>       <td>5</td>
>       <td>6</td>
>       <td>7</td>
>       <td>8</td>
>     </tr>
>   </nattable>
> </a>
> \stopbuffer
> 
> \startxmlsetups xml:testsetups
>     \xmlsetsetup{main}{a|nattable|tr|td|}{xml:*}
> \stopxmlsetups
> 
> \xmlregistersetup{xml:testsetups}
> 
> \startxmlsetups xml:a
>     \xmlflush{#1}
> \stopxmlsetups
> 
> \startxmlsetups xml:nattable
>     \startluacode
>       framestate = lxml.att("#1", "frame")

context(type(framestate))

Here is the problem. The function lxml.att() only prints the attribute,
but returns nothing (framestate = nil). I looked into an old example of
mine where I played with attributes, but it's totally outdated (uses
xml.filters, now mkii only).

Sorry, no solution (goat milk was out).

Peter


[lxml-tex.lua]

function lxml.attribute(id,pattern,a,default)
    local collected = xmlapplylpath(getid(id),pattern)
    if collected then
        attribute(collected,a,default)
    end
end

local function attribute(collected,a,default)
    if collected and #collected > 0 then
        local at = collected[1].at
        local str = (at and at[a]) or default
        if str and str ~= "" then
            contextsprint(notcatcodes,str)
        end
    elseif default then
        contextsprint(notcatcodes,default)
    end
end


>       context(framestate)

does nothing


>       context(true)
>       context.placefigure( { "here" }, "none" , function()
>         context.setupTABLE( { "frame=on" } )
>         context.bTABLE()
>          context.xmlflush("#1")
>         context.eTABLE()
>       end)
>     \stopluacode
> \stopxmlsetups
> 
> \startxmlsetups xml:tr
>     \startluacode
>       context.bTR()
>         context.xmlflush("#1")
>       context.eTR()
>     \stopluacode
> \stopxmlsetups
> 
> \startxmlsetups xml:td
>     \startluacode
>       context.bTD()
>         context.xmlflush("#1")
>       context.eTD()
>     \stopluacode
> \stopxmlsetups
> 
> \starttext
> \xmlprocessbuffer{main}{test}{}
> \stoptext
> 
> question: I have the value "on" in the lua variable "framestate." But
> how can I pass this on to the line
> context.setupTABLE( { "frame=on" } )?
> I tried something like
> context.setupTABLE( { "frame=" .. framestate } )
> but that doesn't work. Any suggestions?
> 
> Thomas
> ___________________________________________________________________________________
> 
> If your question is of interest to others as well, please add an entry
> to the Wiki!
> 
> maillist : ntg-context@ntg.nl /
> http://www.ntg.nl/mailman/listinfo/ntg-context
> webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
> archive  : http://foundry.supelec.fr/projects/contextrev/
> wiki     : http://contextgarden.net
> ___________________________________________________________________________________
> 
> 

___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: xml and lua again

[Hans Hagen]

On 22-10-2011 18:46, Thomas A. Schmitz wrote:
> Hi all,
>
> again, I'm playing a bit with processing my xml in lua. I want a simple
> interface for processing tables (I don't need all the power and
> complexity of cals tables and want to learn something in the process).
> And I thought that collecting the setups in lua might be the easiest
> way, but so far, I haven't been successful. Here's an example:
>
> \startbuffer[test]
> <a>
> <nattable frame="on">
> <tr>
> <td>1</td>
> <td>2</td>
> <td>3</td>
> <td>4</td>
> </tr>
> <tr>
> <td>5</td>
> <td>6</td>
> <td>7</td>
> <td>8</td>
> </tr>
> </nattable>
> </a>
> \stopbuffer
>
> \startxmlsetups xml:testsetups
> \xmlsetsetup{main}{a|nattable|tr|td|}{xml:*}
> \stopxmlsetups
>
> \xmlregistersetup{xml:testsetups}
>
> \startxmlsetups xml:a
> \xmlflush{#1}
> \stopxmlsetups
>
> \startxmlsetups xml:nattable
> \startluacode
> framestate = lxml.att("#1", "frame")
> context(framestate)
> context(true)
> context.placefigure( { "here" }, "none" , function()
> context.setupTABLE( { "frame=on" } )
> context.bTABLE()
> context.xmlflush("#1")
> context.eTABLE()
> end)
> \stopluacode
> \stopxmlsetups
>
> \startxmlsetups xml:tr
> \startluacode
> context.bTR()
> context.xmlflush("#1")
> context.eTR()
> \stopluacode
> \stopxmlsetups
>
> \startxmlsetups xml:td
> \startluacode
> context.bTD()
> context.xmlflush("#1")
> context.eTD()
> \stopluacode
> \stopxmlsetups
>
> \starttext
> \xmlprocessbuffer{main}{test}{}
> \stoptext
>
> question: I have the value "on" in the lua variable "framestate." But
> how can I pass this on to the line
> context.setupTABLE( { "frame=on" } )?
> I tried something like
> context.setupTABLE( { "frame=" .. framestate } )
> but that doesn't work. Any suggestions?

why so complex

\startbuffer[test]
<a>
   <nattable frame="on">
     <tr>
       <td>1</td>
       <td>2</td>
       <td>3</td>
       <td>4</td>
     </tr>
     <tr>
       <td>5</td>
       <td>6</td>
       <td>7</td>
       <td>8</td>
     </tr>
   </nattable>
   <nattable frame="off">
     <tr>
       <td>1</td>
       <td>2</td>
       <td>3</td>
       <td>4</td>
     </tr>
     <tr>
       <td>5</td>
       <td>6</td>
       <td>7</td>
       <td>8</td>
     </tr>
   </nattable>
   <nattable frame="no">
     <tr>
       <td>1</td>
       <td>2</td>
       <td>3</td>
       <td>4</td>
     </tr>
     <tr>
       <td>5</td>
       <td>6</td>
       <td>7</td>
       <td>8</td>
     </tr>
   </nattable>
</a>
\stopbuffer

\startxmlsetups xml:testsetups
     \xmlsetsetup{main}{a|nattable|tr|td|}{xml:*}
\stopxmlsetups

\xmlregistersetup{xml:testsetups}

\startxmlsetups xml:a
     \xmlflush{#1}
\stopxmlsetups

\xmlmapvalue {nattable:frame} {on}  {on}
\xmlmapvalue {nattable:frame} {yes} {on}
\xmlmapvalue {nattable:frame} {off} {off}
\xmlmapvalue {nattable:frame} {no}  {off}

\startxmlsetups xml:nattable
     \placefigure
         [here,none]
         {}
         {
 
\setupTABLE[frame=\xmlval{nattable:frame}{\xmlatt{#1}{frame}}{on}]
             \bTABLE
                 \xmlflush{#1}
             \eTABLE
         }
\stopxmlsetups

\startxmlsetups xml:tr
     \bTR
         \xmlflush{#1}
     \eTR
\stopxmlsetups

\startxmlsetups xml:td
     \bTD
         \xmlflush{#1}
     \eTD
\stopxmlsetups

\starttext
     \xmlprocessbuffer{main}{test}{}
\stoptext

In x-cals.lua / mkiv you can see an example of pure lua solution. It 
boils down to applying a function the the whole table element.

Hans

-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: xml and lua again

[Thomas A. Schmitz]

On 10/24/2011 12:17 PM, Hans Hagen wrote:
> why so complex

Hi Hans,

yes, I'm aware that this procedure is quite silly for this example, this 
was just for myself, for educational purposes. As soon as the setup 
becomes more complex, I thought it might be easier to collect and 
process the options in lua than in tex (as I have done before), but I'm 
running against a wall here (see my exchange with Peter about goat milk 
yesterday). So the real question is: how can I collect data such as an 
attribute value to process it with lua, say in the form

    if lxml.att(t, "frame") == "on" then
       context("Yes, the frame is really on!")
    else
       context("Nope, sorry, it's still off.")
    end

I don't really understand what kind of object a call such as lxml.att(t, 
"frame") produces.

All best

Thomas
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___________________________________________________________________________________

Re: xml and lua again

[Hans Hagen]

On 24-10-2011 14:18, Thomas A. Schmitz wrote:
> On 10/24/2011 12:17 PM, Hans Hagen wrote:
>> why so complex
>
> Hi Hans,
>
> yes, I'm aware that this procedure is quite silly for this example, this
> was just for myself, for educational purposes. As soon as the setup
> becomes more complex, I thought it might be easier to collect and
> process the options in lua than in tex (as I have done before), but I'm
> running against a wall here (see my exchange with Peter about goat milk
> yesterday). So the real question is: how can I collect data such as an
> attribute value to process it with lua, say in the form
>
> if lxml.att(t, "frame") == "on" then
> context("Yes, the frame is really on!")
> else
> context("Nope, sorry, it's still off.")
> end
>
> I don't really understand what kind of object a call such as lxml.att(t,
> "frame") produces.

all lxml.* calls print something to tex, so when you're at the lua end 
and want to stay there you should use the xml.* methods; also, when you 
have an element, say e then there is an e.at table that has all 
attributes


-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
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___________________________________________________________________________________

Re: xml and lua again

[Thomas A. Schmitz]

On 10/24/2011 02:26 PM, Hans Hagen wrote:
>> if lxml.att(t, "frame") == "on" then
>> context("Yes, the frame is really on!")
>> else
>> context("Nope, sorry, it's still off.")
>> end
>>
>> I don't really understand what kind of object a call such as lxml.att(t,
>> "frame") produces.
>
> all lxml.* calls print something to tex, so when you're at the lua end
> and want to stay there you should use the xml.* methods; also, when you
> have an element, say e then there is an e.at table that has all attributes

OK, excuse me for being particularly thick today: there doesn't seem to 
be xml.att, only xml.attribute, so it should be something like:

function tableinit(t)
    if xml.attribute(t, "/", "frame", "off") == "on" then
       context("Yes, the framestate is really on!")
    else
       context("Nope, sorry, it's still off.")
    end
end

(if I understand the definition of xml.attribute correctly: 
id,pattern,a,default)?

Thomas
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___________________________________________________________________________________

Re: xml and lua again

[Hans Hagen]

On 24-10-2011 19:00, Thomas A. Schmitz wrote:
> On 10/24/2011 02:26 PM, Hans Hagen wrote:
>>> if lxml.att(t, "frame") == "on" then
>>> context("Yes, the frame is really on!")
>>> else
>>> context("Nope, sorry, it's still off.")
>>> end
>>>
>>> I don't really understand what kind of object a call such as lxml.att(t,
>>> "frame") produces.
>>
>> all lxml.* calls print something to tex, so when you're at the lua end
>> and want to stay there you should use the xml.* methods; also, when you
>> have an element, say e then there is an e.at table that has all
>> attributes
>
> OK, excuse me for being particularly thick today: there doesn't seem to
> be xml.att, only xml.attribute, so it should be something like:
>
> function tableinit(t)
> if xml.attribute(t, "/", "frame", "off") == "on" then
> context("Yes, the framestate is really on!")
> else
> context("Nope, sorry, it's still off.")
> end
> end
>
> (if I understand the definition of xml.attribute correctly:
> id,pattern,a,default)?

sure, oryou can play with

if xml.filter(t,".[@frame=on]) then

the x-*.lua show some tricks


Hans



-----------------------------------------------------------------
                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
     tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                              | www.pragma-pod.nl
-----------------------------------------------------------------
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Re: xml and lua again

[Thomas A. Schmitz]

On 10/24/11 8:48 PM, Hans Hagen wrote:
> sure, oryou can play with
>
> if xml.filter(t,".[@frame=on]) then
>
> the x-*.lua show some tricks
>

OK, I'm in my "stubborn" mode then: why doesn't this work:

\startbuffer[test]
<a>
   <nattable frame="on">
     <tr>
       <td>1</td>
       <td>2</td>
       <td>3</td>
       <td>4</td>
     </tr>
     <tr>
       <td>5</td>
       <td>6</td>
       <td>7</td>
       <td>8</td>
     </tr>
   </nattable>
</a>
\stopbuffer

\startxmlsetups xml:testsetups
     \xmlsetsetup{main}{a|nattable|tr|td|}{xml:*}
\stopxmlsetups

\xmlregistersetup{xml:testsetups}

\startxmlsetups xml:a
     \xmlflush{#1}
\stopxmlsetups

\startxmlsetups xml:nattable
     \startluacode
       if xml.attribute(t, "/", "frame", "off") == "on" then
       context("Yes, the frame is really on!")
       else
       context("Nope, sorry, it's still off.")
       end
       context(true)
       context.placefigure( { "here" }, "none" , function()
         context.bTABLE()
          context.xmlflush("#1")
         context.eTABLE()
       end)
     \stopluacode
\stopxmlsetups

\startxmlsetups xml:tr
     \startluacode
       context.bTR()
         context.xmlflush("#1")
       context.eTR()
     \stopluacode
\stopxmlsetups

\startxmlsetups xml:td
     \startluacode
       context.bTD()
         context.xmlflush("#1")
       context.eTD()
     \stopluacode
\stopxmlsetups

\starttext
\xmlprocessbuffer{main}{test}{}
\stoptext

I get a lua error here.

Thomas
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Re: xml and lua again

[Wolfgang Schuster]

Am 25.10.2011 um 11:43 schrieb Thomas A. Schmitz:

> On 10/24/11 8:48 PM, Hans Hagen wrote:
>> sure, oryou can play with
>> 
>> if xml.filter(t,".[@frame=on]) then
>> 
>> the x-*.lua show some tricks
>> 
> 
> OK, I'm in my "stubborn" mode then: why doesn't this work:
> 
> […]
> 
> \startxmlsetups xml:nattable
>    \startluacode
>      if xml.attribute(t, "/", "frame", "off") == "on" then
>      context("Yes, the frame is really on!")
>      else
>      context("Nope, sorry, it's still off.")
>      end

     if xml.attribute(lxml.id("#1"), "/", "frame", "off") == "on" then %
       context("Yes, the frame is really on!")
     else %
       context("Nope, sorry, it's still off.")
     end %

Wolfgang
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Re: xml and lua again

[Hans Hagen]

On 25-10-2011 11:43, Thomas A. Schmitz wrote:

> \startxmlsetups xml:nattable
> \startluacode
> if xml.attribute(t, "/", "frame", "off") == "on" then
> context("Yes, the frame is really on!")
> else
> context("Nope, sorry, it's still off.")
> end
> context(true)
> context.placefigure( { "here" }, "none" , function()
> context.bTABLE()
> context.xmlflush("#1")
> context.eTABLE()
> end)
> \stopluacode
> \stopxmlsetups

see Wolfgangs answer

anyway, best move the lua code and wrap it in a function 
"document.MyWhatever" ... now its get defined each time

Hans

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Re: xml and lua again

[Thomas A. Schmitz]

On 10/25/11 12:17 PM, Hans Hagen wrote:
>
> see Wolfgangs answer
>
> anyway, best move the lua code and wrap it in a function
> "document.MyWhatever" ... now its get defined each time
>
> Hans

Wolfgang, Hans,

thanks a lot, this works now. Will now try and move the code to a 
ctxluafile and see if I can make it work again. If not, I'll be back; no 
good deed goes unpunished...

Thomas
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Re: xml and lua again

[Thomas A. Schmitz]

On 10/25/2011 12:27 PM, Thomas A. Schmitz wrote:
> Wolfgang, Hans,
>
> thanks a lot, this works now. Will now try and move the code to a
> ctxluafile and see if I can make it work again. If not, I'll be back; no
> good deed goes unpunished...
>
> Thomas

OK, I'm slowly making progress processing xml in lua. One naive question 
now: how can I have access to and manipulate the textwidth dimension? In 
other words, given

0.4\textwidth

what would be the equivalent in lua code? I tried

0.4 * tex.dimen.textwidth

or

0.4 * tex.dimen["textwidth"]

but couldn't make that work. Also tried grepping the 
tex/context/base/*.lua files for width, but couldn't find anything 
immediately obvious.

Thanks!

Thomas
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Re: xml and lua again

[Wolfgang Schuster]

Am 27.10.2011 um 11:23 schrieb Thomas A. Schmitz:

> On 10/25/2011 12:27 PM, Thomas A. Schmitz wrote:
>> Wolfgang, Hans,
>> 
>> thanks a lot, this works now. Will now try and move the code to a
>> ctxluafile and see if I can make it work again. If not, I'll be back; no
>> good deed goes unpunished...
>> 
>> Thomas
> 
> OK, I'm slowly making progress processing xml in lua. One naive question now: how can I have access to and manipulate the textwidth dimension? In other words, given
> 
> 0.4\textwidth
> 
> what would be the equivalent in lua code? I tried
> 
> 0.4 * tex.dimen.textwidth
> 
> or
> 
> 0.4 * tex.dimen["textwidth"]
> 
> but couldn't make that work. Also tried grepping the tex/context/base/*.lua files for width, but couldn't find anything immediately obvious.


With “tex.dimen[…]” you get the value in scaled points but util-dim.lua provides some functions to convert the value in points, centimeter etc.

\starttext
\startluacode
context.blackrule{ width = number.topoints(tex.dimen["textwidth"]/2) }
\stopluacode
\stoptext

Wolfgang

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Re: xml and lua again

[Thomas A. Schmitz]

On 10/27/2011 11:53 AM, Wolfgang Schuster wrote:
> With “tex.dimen[…]” you get the value in scaled points but util-dim.lua provides some functions to convert the value in points, centimeter etc.
>
> \starttext
> \startluacode
> context.blackrule{ width = number.topoints(tex.dimen["textwidth"]/2) }
> \stopluacode
> \stoptext

Thank you Wolfgang, that's exactly what I was looking for!

All best

Thomas
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Re: xml and lua again

[Hans Hagen]

On 27-10-2011 12:32, Thomas A. Schmitz wrote:
> On 10/27/2011 11:53 AM, Wolfgang Schuster wrote:
>> With “tex.dimen[…]” you get the value in scaled points but
>> util-dim.lua provides some functions to convert the value in points,
>> centimeter etc.
>>
>> \starttext
>> \startluacode
>> context.blackrule{ width = number.topoints(tex.dimen["textwidth"]/2) }
>> \stopluacode
>> \stoptext
>
> Thank you Wolfgang, that's exactly what I was looking for!

or just tex.dimen["textwidth"]/2 .. "sp"


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                                              | www.pragma-pod.nl
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Re: xml and lua again

[Thomas A. Schmitz]

On 10/27/11 13:05, Hans Hagen wrote:
>>> With “tex.dimen[…]” you get the value in scaled points but
>>> util-dim.lua provides some functions to convert the value in points,
>>> centimeter etc.
>>>
>>> \starttext
>>> \startluacode
>>> context.blackrule{ width = number.topoints(tex.dimen["textwidth"]/2) }
>>> \stopluacode
>>> \stoptext
>>
>> Thank you Wolfgang, that's exactly what I was looking for!
>
> or just tex.dimen["textwidth"]/2 .. "sp"

Wait, just so I understand: your solution would imply that 
tex.dimen["textwidth"] holds a number, not a dimension, right? (Because 
you simply concatenate it with a dimension unit). Which makes sense when 
I think of it because lua has no concept of dimensions, only of strings, 
functions, tables, numbers... Whereas the Wolfgang implies that the 
result is already in sp. So who's right?

Thomas
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Re: xml and lua again

[luigi scarso]

On Fri, Oct 28, 2011 at 8:23 AM, Thomas A. Schmitz
<thomas.schmitz@uni-bonn.de> wrote:
> On 10/27/11 13:05, Hans Hagen wrote:
>>>>
>>>> With “tex.dimen[…]” you get the value in scaled points but
>>>> util-dim.lua provides some functions to convert the value in points,
>>>> centimeter etc.
>>>>
>>>> \starttext
>>>> \startluacode
>>>> context.blackrule{ width = number.topoints(tex.dimen["textwidth"]/2) }
>>>> \stopluacode
>>>> \stoptext
>>>
>>> Thank you Wolfgang, that's exactly what I was looking for!
>>
>> or just tex.dimen["textwidth"]/2 .. "sp"
>
> Wait, just so I understand: your solution would imply that
> tex.dimen["textwidth"] holds a number, not a dimension, right? (Because you
> simply concatenate it with a dimension unit). Which makes sense when I think
> of it because lua has no concept of dimensions, only of strings, functions,
> tables, numbers... Whereas the Wolfgang implies that the result is already
> in sp. So who's right?
both -- where is the problem ?
 tex.dimen["textwidth"]/2 .. "sp" gives "xyzsp"

number.topoints(tex.dimen["textwidth"]/2) gives "XYZ.ABSpt"
TeX reads "xyzsp" and drops sp
or
TeX reads "XYZ.ABC.pt" and convert to "xyzsp" and drops sp

The problem  is that
tex.dimen["textwidth"]/2 gives a number, while TeX wants a dimension there

PS
both numbers are signed ( and maybe with spaces here and there, I
don't remember)

-- 
luigi
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Re: xml and lua again

[luigi scarso]

On Fri, Oct 28, 2011 at 8:37 AM, luigi scarso <luigi.scarso@gmail.com> wrote:
soryy, typos

> number.topoints(tex.dimen["textwidth"]/2) gives "XYZ.ABSpt"
number.topoints(tex.dimen["textwidth"]/2) gives "XYZ.ABCpt"

> TeX reads "XYZ.ABC.pt" and convert to "xyzsp" and drops sp
TeX reads "XYZ.ABCpt" and convert to "xyzsp" and drops sp

-- 
luigi
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Re: xml and lua again

[Patrick Gundlach]

>>>> 
>>>> context.blackrule{ width = number.topoints(tex.dimen["textwidth"]/2) }
>> 
>> or just tex.dimen["textwidth"]/2 .. "sp"
> 
> Wait, just so I understand: your solution would imply that tex.dimen["textwidth"] holds a number, not a dimension, right? (Because you simply concatenate it with a dimension unit). Which makes sense when I think of it because lua has no concept of dimensions, only of strings, functions, tables, numbers... Whereas the Wolfgang implies that the result is already in sp. So who's right?

both :)

tex.dimen holds a number, that is the size in points, multiplied by 65536/1pt, so for example 3pt becomes

3pt * 65536
-----------  = 3 * 65536 = 196608
      1pt


This number is also known "sp". So if you store the number 3*65536 in tex.dimen[...], you can say:

my width is \directlua{ tex.dimen[...] / 2}sp (results to "my width is 196608sp", which you can use as an argument to whatever needs a length)

or

my width is \directlua{  number_to_points(tex.dimen[...]) } where number_to_points is something like

number_to_points = function (amount_in_sp) 
  in_pt = tostring(amount_in_sp / 65536) 
  return in_pt .. "pt"
end

which gives "3pt". 

Patrick

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Re: xml and lua again

[Thomas A. Schmitz]

On 10/28/11 08:44, Patrick Gundlach wrote:
>
>
>>>>>
>>>>> context.blackrule{ width = number.topoints(tex.dimen["textwidth"]/2) }
>>>
>>> or just tex.dimen["textwidth"]/2 .. "sp"
>>
>> Wait, just so I understand: your solution would imply that tex.dimen["textwidth"] holds a number, not a dimension, right? (Because you simply concatenate it with a dimension unit). Which makes sense when I think of it because lua has no concept of dimensions, only of strings, functions, tables, numbers... Whereas the Wolfgang implies that the result is already in sp. So who's right?
>
> both :)
>
> tex.dimen holds a number, that is the size in points, multiplied by 65536/1pt, so for example 3pt becomes
>
> 3pt * 65536
> -----------  = 3 * 65536 = 196608
>        1pt
>
>
> This number is also known "sp". So if you store the number 3*65536 in tex.dimen[...], you can say:
>
> my width is \directlua{ tex.dimen[...] / 2}sp (results to "my width is 196608sp", which you can use as an argument to whatever needs a length)
>
> or
>
> my width is \directlua{  number_to_points(tex.dimen[...]) } where number_to_points is something like
>
> number_to_points = function (amount_in_sp)
>    in_pt = tostring(amount_in_sp / 65536)
>    return in_pt .. "pt"
> end
>
> which gives "3pt".
>
> Patrick
>

Luigi, Patrick,

thanks for your explanations! The point of my question was: can I feed 
the content of tex.dimen["textwidth"] directly back to TeX, and the 
answer to this appears to be "no"; you need to add some unit to it 
(otherwise, you get an error message). Which was a bit confusing to me 
at first, because the name tex.dimen implies that it holds a "real" 
dimension, like \newdim does.

Thomas
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Re: xml and lua again

[Wolfgang Schuster]

Am 28.10.2011 um 08:55 schrieb Thomas A. Schmitz:

> Luigi, Patrick,
> 
> thanks for your explanations! The point of my question was: can I feed the content of tex.dimen["textwidth"] directly back to TeX, and the answer to this appears to be "no"; you need to add some unit to it (otherwise, you get an error message). Which was a bit confusing to me at first, because the name tex.dimen implies that it holds a "real" dimension, like \newdim does.


You can get the same value in TeX when you print the value of a dimension with \number:

\starttext

\scratchdimen=3pt

\number\scratchdimen

\ctxlua{context(tex.dimen["scratchdimen"])}

\stoptext

Wolfgang

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Re: xml and lua again

[Hans Hagen]

On 28-10-2011 10:35, Wolfgang Schuster wrote:
>
> Am 28.10.2011 um 08:55 schrieb Thomas A. Schmitz:
>
>> Luigi, Patrick,
>>
>> thanks for your explanations! The point of my question was: can I feed the content of tex.dimen["textwidth"] directly back to TeX, and the answer to this appears to be "no"; you need to add some unit to it (otherwise, you get an error message). Which was a bit confusing to me at first, because the name tex.dimen implies that it holds a "real" dimension, like \newdim does.
>
>
> You can get the same value in TeX when you print the value of a dimension with \number:
>
> \starttext
>
> \scratchdimen=3pt
>
> \number\scratchdimen
>
> \ctxlua{context(tex.dimen["scratchdimen"])}
>
> \stoptext

which also means that you can say \scratchcounter=\scratchdimen and test 
dimens as if they are numbers ... this is why we can have

\let\ifzeropt\ifcase

which probably no one ever noticed in the source.

Hans


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Re: xml and lua again

[Hans Hagen]

Hi Thomas,

> thanks for your explanations! The point of my question was: can I feed
> the content of tex.dimen["textwidth"] directly back to TeX, and the
> answer to this appears to be "no"; you need to add some unit to it
> (otherwise, you get an error message). Which was a bit confusing to me
> at first, because the name tex.dimen implies that it holds a "real"
> dimension, like \newdim does.

Just switch to philosopher mode for a while and ask yourself what 
implications that would have in the rather fuzzy world of printing.

What is a 'real' dimension? What we call points (pt) is in other 
application also called points but happens to be basepoints in our 
universe (bp). Also, imagine that in good american tradition the 
dimension would have been inches while we all moved on to meters ...

So, Knuth foresaw this (and also wanted predictable calculations and 
wanted to avoid unportable floating points) so he came up with his own 
unit: scaled points. So, a \dimen is just a \count but consider it 
tagged to show you pt for convenience when printed (\the) and the parser 
permits you to enter these numbers as pt/bp/dd/cc/cm/mm etc.

At the lua end all are just integers (with some limited size but that 
might change as Taco and I want to play a bit with adding a couple of 
bytes and see to what extent that will break things).

In metapost the internal unit is bp (because it targets at postscript) 
and there cm, mm etc are just variables that one multiplies with so 
there you can change the universe by just saying "in := cm".

Skips are another story (not to speak of boxes as we do have a dimendef 
but not a boxdef of inserts which are yet another class of animals).

Hans


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Re: xml and lua again

[Thomas A. Schmitz]

On 10/28/11 10:56, Hans Hagen wrote:
> Just switch to philosopher mode for a while and ask yourself what
> implications that would have in the rather fuzzy world of printing.
>
> What is a 'real' dimension? What we call points (pt) is in other
> application also called points but happens to be basepoints in our
> universe (bp). Also, imagine that in good american tradition the
> dimension would have been inches while we all moved on to meters ...
>
> So, Knuth foresaw this (and also wanted predictable calculations and
> wanted to avoid unportable floating points) so he came up with his own
> unit: scaled points. So, a \dimen is just a \count but consider it
> tagged to show you pt for convenience when printed (\the) and the parser
> permits you to enter these numbers as pt/bp/dd/cc/cm/mm etc.
>
> At the lua end all are just integers (with some limited size but that
> might change as Taco and I want to play a bit with adding a couple of
> bytes and see to what extent that will break things).
>
> In metapost the internal unit is bp (because it targets at postscript)
> and there cm, mm etc are just variables that one multiplies with so
> there you can change the universe by just saying "in := cm".
>
> Skips are another story (not to speak of boxes as we do have a dimendef
> but not a boxdef of inserts which are yet another class of animals).

Thanks for this philosophical explanation - I guess I'll have to reread 
these passages in the TeX book. I'm looking forward to your experiments :-)

Thomas
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Re: xml and lua again

[luigi scarso]

On Fri, Oct 28, 2011 at 10:56 AM, Hans Hagen <pragma@wxs.nl> wrote:
> Hi Thomas,
>
>> thanks for your explanations! The point of my question was: can I feed
>> the content of tex.dimen["textwidth"] directly back to TeX, and the
>> answer to this appears to be "no"; you need to add some unit to it
>> (otherwise, you get an error message). Which was a bit confusing to me
>> at first, because the name tex.dimen implies that it holds a "real"
>> dimension, like \newdim does.
>
> Just switch to philosopher mode for a while and ask yourself what
> implications that would have in the rather fuzzy world of printing.
>
> What is a 'real' dimension? What we call points (pt) is in other application
> also called points but happens to be basepoints in our universe (bp). Also,
> imagine that in good american tradition the dimension would have been inches
> while we all moved on to meters ...
>
> So, Knuth foresaw this (and also wanted predictable calculations and wanted
> to avoid unportable floating points) so he came up with his own unit: scaled
> points.
just to see the floating point in action:
\starttext
\startluacode
context(collectgarbage('count')," KB are ",collectgarbage('count')*1024," byte")
\stopluacode
\stoptext


collectgarbage('count')  returns the total memory in use by Lua (in Kbytes).

>
> At the lua end all are just integers (with some limited size but that might
> change as Taco and I want to play a bit with adding a couple of bytes and
> see to what extent that will break things).
hm, I'm bit loss here.
In CWEB I see
define max_dimen        0x3FFFFFFF
so I suppose that it's a kind of int
But the type of tex.dimen is number as is the type of math.sqrt(2) as
we can see in
context(type(tex.dimen['textwidth']))
context(type(math.sqrt(2)))

i.e it's a Lua number -- a floating point.
So a kind of conversion can happen between a  floating point and a sp
number (which has a limited range)
Of course Lua has its routines, but probably they differs from TeX
If I recall correctly, both use 32 bits, but if you extend to lets say
48 bit then the TeX routines are not good anymore.

Well, I'm not sure it's right, of course.



-- 
luigi
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Re: xml and lua again

[Hans Hagen]

> i.e it's a Lua number -- a floating point.
> So a kind of conversion can happen between a  floating point and a sp
> number (which has a limited range)
> Of course Lua has its routines, but probably they differs from TeX
> If I recall correctly, both use 32 bits, but if you extend to lets say
> 48 bit then the TeX routines are not good anymore.
>
> Well, I'm not sure it's right, of course.

The lua numbers have enough precision to cast on the tex numbers (with 
rounding) but in practice I don't care too much. As we have standardized 
floats the behaviour is predictable. We could probably go completely 
float at the tex end but too many datastructures expect an integer so 
it's not worth the trouble.

Hans


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