RE: Usage scenarios of 'treat as'

Yes, "treat as" is there almost entirely for systems that do pessimistic
static type checking.

It can also, however, be used as an assertion mechanism, to document that
you expect a particular expression to return a particular type of value and
trigger a failure if it doesn't.

Michael Kay
http://www.saxonica.com/

> -----Original Message-----
> From: Frans Englich [mailto:frans.englich@xxxxxxxxx] 
> Sent: 29 August 2005 22:07
> To: xsl-list@xxxxxxxxxxxxxxxxxxxxxx
> Subject:  Usage scenarios of 'treat as'
> 
> 
> Hi,
> 
> I'm curious on usage scenarios for the 'treat as' expression, 
> in particular 
> for when XSL-T 2.0 is the host language(if that matters).
> 
> In XPath 2.0 is verification of an operand's type(the 
> function conversion 
> rules) done at runtime(implementation dependent if guaranteed 
> runtime type 
> errors are detected statically), unless the implementation implements 
> "pessimistic" static type checking. (Right?)
> 
> In what case is the 'treat as' expression useful, or 
> required, when the 
> implementation does not do pessimistic, static type checking? 
> (that is, usage 
> scenarios which applies for all implementations regardless of 
> what optional 
> features that are implemented.)
> 
> From what I can tell, the 'treat as' expression is only 
> useful when writing 
> code that must work on implementations that implement 
> pessimistic type 
> checking.
> 
> Clarification, elaboration, & correction is appreciated.
> 
> 
> Cheers,
> 
> 		Frans