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[css3-layout] A shortcut with numbers instead of letters in a template

From: Bert Bos <bert@w3.org>
Date: Fri, 2 Dec 2011 12:42:39 +0100
To: W3C style mailing list <www-style@w3.org>
Message-Id: <201112021242.40040.bert@w3.org>
On re-reading the documentation of the template layout implementation in 
HTMLayout by Andrew Fedoniouk and Ivan Goroun 
(http://www.terrainformatica.com/w3/flex-layout/flex-layout.htm) I 
noticed something that I hadn't seen before; or maybe seen but 
forgotten:

The template syntax allows numbers as a shortcut for simple (but 
probably common) cases. E.g. if you have a document like this

    <BODY>
      <DIV>North...</DIV>
      <DIV>West...</DIV>
      <DIV>East...</DIV>
      <DIV>South...</DIV>

you could write this layout:

    BODY { display: ". 1 ."
                    "2 . 3"
                    ". 4 ." }

instead of the equivalent:

    BODY { display: ". a ."
                    "b . c"
                    ". d ." }
    DIV:nth-child(1) { position: a }
    DIV:nth-child(2) { position: b }
    DIV:nth-child(3) { position: c }
    DIV:nth-child(4) { position: d }

I.e., the numbers refer directly to the children of the template 
element. The designated children are automatically positioned in the 
given slot, without having to write any rules for them.

Advantages:

  - No need to invent names for the slots in the template.
  - Shorter: avoids extra rules and selectors with pseudo-classes.

Disadvantages:

  - An extra thing to learn.
  - Spaces between slots in a templates are required (rather than
    optional), because numbers can have more than one digit.

Clearly, this shortcut is limited to positioning child elements (not 
other descendants), and to slots with at most one element in it. You 
still need named slots for the other cases.


So the question is, do the advantages outweigh the disadvantages?



Bert
    
PS. Tracker code: ISSUE-201
http://www.w3.org/Style/CSS/Tracker/issues/201

-- 
  Bert Bos                                ( W 3 C ) http://www.w3.org/
  http://www.w3.org/people/bos                               W3C/ERCIM
  bert@w3.org                             2004 Rt des Lucioles / BP 93
  +33 (0)4 92 38 76 92            06902 Sophia Antipolis Cedex, France
Received on Friday, 2 December 2011 11:43:13 GMT

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