6 ms·

I am not sure I understand your point, how do you expect to be able to apply a style across multiple elements in a HTML document using attributes of existing el

I am not sure I understand your point, how do you expect to be able to apply a style across multiple elements in a HTML document using attributes of existing elements? Nevertheless you'd have to define selectors or use classes, even XPATH had to come along for XML. Then you would also have to define property names and value. And you pretty much invented CSS. To apply it by classification, it has to be declared independent from your document tree, then you might as well separate it.

saghm 9y ago
From the example of FOSI in the article, it looks like the SGML elements aren't directly contained within the elements they style but refer them them from attributes (gi="h1", gi="h2", etc.), which is actually more similar in functionality to having external CSS stylesheets than inline CSS (which is what I think you're referring to).
- tarikjn 9y ago
  Yes I saw this and though you might be referring to this, but it's still roughly the same, by defining these attribute names and selectors, you are still defining a language, you don't save much to learn. There is not much else to the CSS language.
  - saghm 9y ago
    I think that tannhaeuser was just stating a preference that we use the same syntax for both the content (HTML) and the style markup (FOSI vs. CSS)
- tannhaeuser 9y ago
  FWIW, SGML also has LINKTYPEs (in addition to DOCTYPEs) for declaring presentation properties using normal attribute declaration syntax. A LINKTYPE can contain a state automaton assigning link attribute values to content elements and for transitioning to other states, but, unlike CSS, doesn't use regular patterns. This system makes sense for print, where a standard task is to assign different horizontal margins on even and odd pages. Using SGML LINK, this can be implemented by declaring two states transitioning to one another over page elements. A regular expression pattern language like CSS, OTOH, can't express the necesssary logic, hence CSS has a large number of extra predicates.
  - Sharlin 9y ago
    Well, if CSS actually supported full regular expressions in selectors, even/odd wouldn't need custom predicates.
    - tannhaeuser 9y ago
      Yes, but only if grouping of subexpressions or non-terminals in grammar productions are allowed (they aren't in CSS). To elaborate, the problem at hand is to assign different properties to the even and odd elements, resp., of a sequence using just the sequence, alternation, and Kleene star operators in two rules. For example, the rules for the first few items (as) are as follows: even -> a a | a a a a | .. odd -> a | a a a | .. A solution using grouping of subexpressions/non-terminal symbols in grammar rules: even -> ( a a )* odd -> even a
      - marcosdumay 9y ago
        That's a full logic language (like prolog) for selecting things. It's very easy to mess up a prolog program and destroy its performance, so it's not a good thing to have on a web standard. Maybe something more functional instead of logic would be better.
        tannhaeuser 9y ago
        I was just trying to make the point that in core CSS basic even/odd selection isn't possible, hence the :nth-child()/:nth-of-type() CSS selectors were introduced. SGML LINK doesn't have this particular problem, as it just encodes an automaton using transitions. For example, you can say <!link even x #postlink odd [ background-color=gray ]> <!link odd x #postlink even [ background-color=white ]> where "#postlink even ..." means "upon an 'x' element, use gray and transition to the 'odd' link set", from where it transitions back to 'even' state on the next 'x' and so on, so that the current link set is toggled between the even and odd states. You can also set a state for child content with #uselink.
        zmonx 9y ago

saghm 9y ago

From the example of FOSI in the article, it looks like the SGML elements aren't directly contained within the elements they style but refer them them from attributes (gi="h1", gi="h2", etc.), which is actually more similar in functionality to having external CSS stylesheets than inline CSS (which is what I think you're referring to).

tarikjn 9y ago
Yes I saw this and though you might be referring to this, but it's still roughly the same, by defining these attribute names and selectors, you are still defining a language, you don't save much to learn. There is not much else to the CSS language.
- saghm 9y ago
  I think that tannhaeuser was just stating a preference that we use the same syntax for both the content (HTML) and the style markup (FOSI vs. CSS)
tannhaeuser 9y ago
FWIW, SGML also has LINKTYPEs (in addition to DOCTYPEs) for declaring presentation properties using normal attribute declaration syntax. A LINKTYPE can contain a state automaton assigning link attribute values to content elements and for transitioning to other states, but, unlike CSS, doesn't use regular patterns. This system makes sense for print, where a standard task is to assign different horizontal margins on even and odd pages. Using SGML LINK, this can be implemented by declaring two states transitioning to one another over page elements. A regular expression pattern language like CSS, OTOH, can't express the necesssary logic, hence CSS has a large number of extra predicates.
- Sharlin 9y ago
  Well, if CSS actually supported full regular expressions in selectors, even/odd wouldn't need custom predicates.
  - tannhaeuser 9y ago
    Yes, but only if grouping of subexpressions or non-terminals in grammar productions are allowed (they aren't in CSS). To elaborate, the problem at hand is to assign different properties to the even and odd elements, resp., of a sequence using just the sequence, alternation, and Kleene star operators in two rules. For example, the rules for the first few items (as) are as follows: even -> a a | a a a a | .. odd -> a | a a a | .. A solution using grouping of subexpressions/non-terminal symbols in grammar rules: even -> ( a a )* odd -> even a
    - marcosdumay 9y ago
      That's a full logic language (like prolog) for selecting things. It's very easy to mess up a prolog program and destroy its performance, so it's not a good thing to have on a web standard. Maybe something more functional instead of logic would be better.
      - tannhaeuser 9y ago
        I was just trying to make the point that in core CSS basic even/odd selection isn't possible, hence the :nth-child()/:nth-of-type() CSS selectors were introduced. SGML LINK doesn't have this particular problem, as it just encodes an automaton using transitions. For example, you can say <!link even x #postlink odd [ background-color=gray ]> <!link odd x #postlink even [ background-color=white ]> where "#postlink even ..." means "upon an 'x' element, use gray and transition to the 'odd' link set", from where it transitions back to 'even' state on the next 'x' and so on, so that the current link set is toggled between the even and odd states. You can also set a state for child content with #uselink.
      - zmonx 9y ago