W3C home > Mailing lists > Public > www-style@w3.org > April 1996

Re: URLs in CSS

From: Abigail <abigail@tungsten.gn.iaf.nl>
Date: Mon, 15 Apr 1996 21:01:21 +0200 (MET DST)
Message-Id: <199604151901.VAA08043@tungsten.gn.iaf.nl>
To: www-style@w3.org
Scott E. Preece wrote:
++ 
++ From: Hakon Lie <howcome@w3.org>
++ |  
++ |  Several CSS properties take URL values. Up to now, URLs have been
++ |  identified with quotes. This works quite well for absolute links:
++ |  
++ |    BODY { background: "http://foo.com/png/marble" }
++ ---
++ 
++ I would *strongly* urge that quotes have no special semantics beyond
++ grouping characters into a string - it's just too confusing.  You *need*
++ to have a way of unambiguously indicating that a sequenec of characters
++ is a single value, regardless of its context, and that should be what
++ quotes mean.
++ 
++ I'm pretty sure that's what the formal grammar says - that a
++ sequence of characters surrounded by quotes is a string.  The quotes
++ should never be visible to the parser at all - the lexer should have
++ used them to turn the surrounded characters into a token of type string.

I agree with Scott. Quotes should be used to group characters;
nothing else.

++ ---
++ |  Here are some suggestions for alternative schemes;
++ |  
++ |    BODY { background: [http://foo/bar] }
++ |    BODY { background: url:http://foo/bar }
++ |    BODY { background: href:red }
++ |    BODY { background: url:red }
++ |    BODY { background: url(red) }
++ |    BODY { background: url(http://foo/bar) }

Or:
BODY { background: <URL:http://foo/bar> }

It has the advantage that this notation is already in use; though
I do not know if there is any formal status for it.

++ I'd slightly prefer url(...) over href(...). It generalizes naturally to
++ explicitly indicating other units.  I would avoid using another colon,
++ just to make life easier for the parser.
++ 
++ ---
++ |  Also, should the identification be optional for absolute URLs?:
++ |  
++ |    BODY { background: http://foo/bar } 
++ ---
++ 
++ I guess I would require it wherever the syntax allows alternative units
++ that could be confused - that is, if you had a property whose value was
++ *always* a URL, it would be OK to omit it there, but it would be
++ required wheever the units alternatives left it open to interpretation.
++ While it's unlikely that the name of a color would be a string that
++ started "http:", it's quite possible that for some other property it
++ *would* be ambigous.  For instance, if you had a "Footer" property, you
++ would have no way of knowing whether "http://..." was meant to be a
++ string that would be printed in the footer or meant to be a URL where
++ the actual footer contents would be found.

Indeed, specially since an URL can have another scheme than http.
For now, I can only think of using ftp in this context, but that
can change in the future.


Abigail

-- 
<URL: http://www.edbo.com/abigail/>  (Changed)
Received on Monday, 15 April 1996 15:01:29 GMT

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