Re: [dssslist] 1) 'the principal port'; 2) port selection?

["Pavel Tolkachev" <pavel.tolkachev@xxxxxx>]

Hello Sean,

I am no way DSSSL expert, but I believe 12.4.3 (sosofos) gives the answers: If the object (added by make-expression) is labeled, "and the label is the one that is mapped by the content map" then it is appended to the stream attached to the port to which the lable is mapped; if it is unlabeled, there must be a principal (i.e. unnamed) port and the object goes to its stream..

This is the example I found in DocBook stylesheets:

(make table-part
      content-map: '((thead header)
            (tbody #f)
            (tfoot footer))
      ($process-colspecs$ (current-node))
      (process-children)
      (make-table-endnotes))

My understanding is that every object labeled by thead will go to the header port's stream, tbody will go to the principal port and tfoot will go to the footer's stream.. ,

Hope this will help,
Pavel



                                                                                                                                                       
                      Sean Champ                                                                                                                       
                      <gimbal@xxxxxxxxx        To:       dssslist@xxxxxxxxxxxxxxxxxxxxxx                                                               
                      tar.org>                 cc:                                                                                                     
                                               Subject:  [dssslist] 1) 'the principal port'; 2) port selection?                                        
                      09/06/2004 01:37                                                                                                                 
                      AM                                                                                                                               
                      Please respond to                                                                                                                
                      dssslist                                                                                                                         
                                                                                                                                                       
                                                                                                                                                       




Hello,

I've some questions, myself, regarding 'ports'.

I hope you'll pardon if I skip any start-of-page exposition.

I have two questions:


** 1) "the principal port" (of what?)

In section 12.6.28.2 of the DSSSL standard [1] : regarding the
"multi-modes" property of the multi-mode flow object  class, it says:

   The specification of a port is either #f specifying the principal
   port or a symbol specifying a named port.


Now, I understand the notion of /a/ principal port - generally, as
removed from any particular flow object. When the standard says /the/
principal port, though - I'm not meaning to pick at the standard,
here, honestly, but just to check at my understanding of it - it does
mean /the principal port of the flow-object being created/ --  yah?

(So, here, "the principal port" could  mean: the principal port of the
multimode flow-object being created .. ?)



** 2) finding a a "principal port", or a named port, of an arbitrary
   flow object

(continuing on the text of the prior)

...Still, I do not understand what it /means/, outside of the basic
wording and the terminology.  I would appreciate any help, here.



Here is some of what I do understand, regarding the principal port:


 - In the 'multi-modes' property of a multi-mode flow-object (that
   property's value being - I presume - some manner of a list), there
   must exist exist a "principal port" specifier.

 - The principal port may be made to contain things.


...and that's about all that I understand of it, honestly.



So, I guess that my main question would be:

  How would one go about, for pushing a flow object into  the
  principal port of an (arbitrary) multi-mode flow-object X?



Like, for example, if I want to add a 'box' flow-object into the
principal port (or any named port) of a 'multi-mode' flow object,
somewhere off in the blue ...

I suppose I could try something like the following, for at least
creating a box:

 (make box ; or however it would be said
  <stuff goes here>))

...but how could I manage to push the "value" of that box into the
desired "port" of the desired multi-mode flow object?

(How would I even "find" the principal port - or a named port - if
I'd been given the multi-mode flow object, directly ? - like, if the
selected flow-object had been stored as the value of a "local" variable.)




Thank you


--
sean



---


Footnotes:
[1]  I think I've heard that it is a draft standard  - the one 'freely'
     available online, is the standard that I meant to refer to.






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