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Re: Question on using xs:pattern to restrict xs:dateTime

• To: "Henry S. Thompson" <ht@c...>
• Subject: Re: Question on using xs:pattern to restrict xs:dateTime
• From: "Dare Obasanjo" <kpako@y...>
• Date: Fri, 4 Jan 2002 08:27:15 -0800
• Cc: "xml-dev" <xml-dev@l...>
• References: <001901c19560$7e950920$0500a8c0@carnage><f5b8zbexrrq.fsf@c...><00ba01c19537$81d7fbc0$0500a8c0@carnage> <f5br8p6w9k1.fsf@c...>

----- Original Message -----
From: "Henry S. Thompson" <ht@c...>
To: "Dare Obasanjo" <kpako@y...>
Cc: "xml-dev" <xml-dev@l...>
Sent: Friday, January 04, 2002 5:05 AM
Subject: Re:  Question on using xs:pattern to restrict xs:dateTime


> > From what I've seen the pattern facet can easily be made to create
> > illegal restrictions which none of the validating parsers I have
> > tried warns about.
>
> Um, now I'm confused -- how does your example's use of pattern create
> 'illegal restrictions'?

I guess "illegal restriction" is the wrong terminology.

> > > > <xsd:simpleType name="myTimeType">
> > > >       <xsd:restriction base="xsd:dateTime">
> > > >         <xsd:pattern value="\d\d:\d\d(:\d\d)?" />
> > > >          <xsd:whiteSpace value="collapse" />
> > > >       </xsd:restriction>
> > > > </xsd:simpleType>
>
> It's true there are no valid instances of this type, but that's not
> illegal, just useless.  It's open to processors to issue warnings when
> a type has no members, but they're not required to.
>

This is unfortunate because a schema author may create the above type and
assume it is a valid restriction of the xs:dateTime type since validating
parsers never complain only for it to fail whenever used with a [seemingly]
cryptic error message.

I guess it probably would be difficult to validate that the contents of the
value space of the pattern facet are a subset of the contents of the value
space of the original type and thus most (or all?) validating parsers just
don't do it. . *sigh*

--
THINGS TO DO IF I BECOME AN EVIL OVERLORD #16
I will never utter the sentence "But before I kill you, there's just
one thing I want to know."


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• References:
  • Question on using xs:pattern to restrict xs:dateTime
    • From: "Dare Obasanjo" <kpako@y...>
  • Re: Question on using xs:pattern to restrict xs:dateTime
    • From: ht@c... (Henry S. Thompson)
  • Re: Question on using xs:pattern to restrict xs:dateTime
    • From: "Dare Obasanjo" <kpako@y...>
  • Re: Question on using xs:pattern to restrict xs:dateTime
    • From: ht@c... (Henry S. Thompson)

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