- From: John Boyer <boyerj@ca.ibm.com>
- Date: Tue, 29 May 2007 19:08:38 -0700
- To: Ulrich Nicolas Lissé <unl@dreamlab.net>
- Cc: ebruchez@orbeon.com, public-forms@w3.org, www-forms-editor@w3.org, www-forms-editor-request@w3.org
- Message-ID: <OF4C04B1AC.BDC022EF-ONCA2572EB.000B08B6-882572EB.000BC78A@ca.ibm.com>
I agree with Ulrich. The meaning of empty string is clear, and a string with spaces in it is not empty because it has spaces in it. I do agree that this is different than what a user-friendly interpretation might mean, but this would not be the only place where such technicalities cause us a little grief. Here are a few other favorites: 1) having to say true() and false() rather than true and false 2) Having empty string not be the same thing as zero in XPath mathematical operations 3) Empty string being unacceptable lexically for many schema datatypes Still, these don't mean our issues are ill-defined. Just that right now a form author would have to do more work to address the situation when there should be no distinction between two things like whitespace string and empty string. John M. Boyer, Ph.D. STSM: Lotus Forms Architect and Researcher Chair, W3C Forms Working Group Workplace, Portal and Collaboration Software IBM Victoria Software Lab E-Mail: boyerj@ca.ibm.com Blog: http://www.ibm.com/developerworks/blogs/page/JohnBoyer Ulrich Nicolas Lissé <unl@dreamlab.net> Sent by: www-forms-editor-request@w3.org 05/29/2007 02:43 PM To ebruchez@orbeon.com cc public-forms@w3.org, www-forms-editor@w3.org Subject Re: Required but empty Erik, I think an empty string is clearly a zero-length string. While this might be owed to a technical background I see the usability issue. However, you could avoid whitespace-only strings from being submitted with <xf:bind ... constraint="string-length(normalize-space(.)) > 0"/> or by defining a subtype of xs:string disallowing whitespace-only character sequences. This is a bit tedious for the for author, but I don't think we should handle empty and whitespace-only strings equally in general. I can't think of a half-decent use case for whitespace-only strings right now, but I'm convinced some form author will have a use case requiring white space to submit. Regards, Uli. Erik Bruchez wrote: > > All, > > I have a doubt about the meaning of "empty" in the wording "required but > empty" (which appears in 11.2.3 and 4.3.5). > > It seems that "empty" could either mean: > > 1. A zero-length string (clear technical interpretation) > 2. A string empty as per #1 above, or a string with only white-space > (human-friendly interpretation) > > Imagine a user entering by error a space in an input field. Visually, > with most agents (typically web browsers), you can't tell whether the > field is empty according to #1 above, or contains white space. So to the > user, the field is "empty". > > But if the XForms implementation implements #1, then this visually empty > field will be considered non-empty, and pass submission even if required. > > This would favor an interpretation of "empty" where not only strictly > empty strings are "empty", but also strings containing only white space. > > At the very least, the spec should say whether it means #1, #2, or > implementation-dependent. > > -Erik > -- Ulrich Nicolas Lissé
Received on Wednesday, 30 May 2007 02:09:17 UTC