Altova Mailing List Archives


Re: [xsl] () eq () vs () = ()

From: David Carlisle <davidc@---.--.-->
To: xsl-list@-----.------------.---
Date: 9/30/2011 11:01:00 AM
On 30/09/2011 11:48, Andrew Welch wrote:
> () = () returns false
>
> deep-equals((),()) returns true
>
> That's interesting, I'm guessing it has to be a 'just because'


it can be sort of justified

deep-equals tries to tell you if the sequences passed in as arguments 
are equal or not and () and () being the same are equal as sequences.

eq and = never consider the sequence as a whole, they only consider 
individual items

eq just considers single items and (because if sql heritage, probably, 
empty sequences)  so returns () when given ().

= is an existential quantified comparison and the answer to
"is there an item in the first sequence equal to an item in the second"
is trivially false, since there are no items, so = returns false.

So, each operator (with the possible exception of eq, which would 
perhaps most naturally have been defined to be an error on () eq () )
has a natural justification, and so the user will never be confused and 
order is restored to the universe...

David


________________________________________________________________________
The Numerical Algorithms Group Ltd is a company registered in England
and Wales with company number 1249803. The registered office is:
Wilkinson House, Jordan Hill Road, Oxford OX2 8DR, United Kingdom.

This e-mail has been scanned for all viruses by Star. The service is
powered by MessageLabs. 
________________________________________________________________________

--~------------------------------------------------------------------
XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list
To unsubscribe, go to: http://lists.mulberrytech.com/xsl-list/
or e-mail: <mailto:xsl-list-unsubscribe@l...>
--~--

Disclaimer

These Archives are provided for informational purposes only and have been generated directly from the Altova mailing list archive system and are comprised of the lists set forth on www.altova.com/list/index.html. Therefore, Altova does not warrant or guarantee the accuracy, reliability, completeness, usefulness, non-infringement of intellectual property rights, or quality of any content on the Altova Mailing List Archive(s), regardless of who originates that content. You expressly understand and agree that you bear all risks associated with using or relying on that content. Altova will not be liable or responsible in any way for any content posted including, but not limited to, any errors or omissions in content, or for any losses or damage of any kind incurred as a result of the use of or reliance on any content. This disclaimer and limitation on liability is in addition to the disclaimers and limitations contained in the Website Terms of Use and elsewhere on the site.