Re: [xsl] Understanding Identity Transformations

["Joris Gillis" <roac@xxxxxxxxxx>]

Tempore 21:55:30, die 02/12/2005 AD, hinc in  
xsl-list@xxxxxxxxxxxxxxxxxxxxxx scripsit Karl Stubsjoen <kstubs@xxxxxxxxx>:

> Wow.. that is easy except that I do not understand your notice
> explanation... the difference between your not( ... ) and your !=.

"@cat != 'BLUE'": will be true if the context node has a 'cat' attribute  
*and* if it has a 'cat' attribute not equal to 'BLUE'. So it's the same as  
"boolean(@cat) and not(@cat='BLUE')"

"not(@cat='BLUE')": will be true if the context node has no 'cat'  
attribute *or* if it has a 'cat' attribute not equal to 'BLUE'. So it's  
equal to "not(@cat) or not(@cat='BLUE')"

Wow... so much boolean logic that it doesn't seem logical anymore...

> So what is the difference then?  I don't get it.

The difference is that '!=' will work and 'not(...=...)' will not.
Now don't ask me why:)
The reason can probably found at http://www.w3.org/TR/xpath.html#booleans  
, but I know it rather from experience than from any documentation.



regards,
--
Joris Gillis (http://www.ticalc.org/cgi-bin/acct-view.cgi?userid=38041)
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