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Re: [proposal] XPath API for Java

• To: xml-dev@l...
• Subject: Re: [proposal] XPath API for Java
• From: ari@c... (K. Ari Krupnikov)
• Date: 20 Sep 2003 15:58:06 -0700
• In-reply-to: <3F6CBE42.8070800@p...>
• References: <3F6C9777.6000300@d...><86ekybnt0e.fsf@f...> <3F6CBE42.8070800@p...>
• Sender: ari@l...
• User-agent: Gnus/5.09 (Gnus v5.9.0) Emacs/21.3

Bill de hÓra <bill.dehora@p...> writes:

> K. Ari Krupnikov wrote:
> 
> 
> > I think an interface with only a single method is of limited value,
> > given the range of XPath uses.
> 
> That's what I thought. I've sitting on this for a few months, thinking
> it was too trivial. But then I thought if that's all you need, so be
> it, no point increasing the surface area for the sake of it. I'm also
> curious to find out if that's all anyone else needs ;)

I'm basing this more on what two Java XPath implementations have in
common than on what a user might conceivably find useful.

> > I would also consider getBooleanValue() and getStringValue().
> 
> What I do now is cast base on the xpath I'm putting in, ie if I put in
> a path with text() I can make some assumptions about what's coming
> back.

Expression.getMatchingNodes().item(0).toString is not the same as
Expression.getStringValue(), the latter, in XPath, gives you a
concatenation of all descendant text nodes.

> It's untyped and therefor risky, but the xpath is close by if
> there's a problem.

getBooleanValue() would follow XPath hopefully 1.0) rules of casting
things to booleans, not Java. Same for numbers.

> that means you have to have
> extra error handling goo to deal with time someone puts in a path
> not that doesn't, but can't evaluate to the type. But if it was
> limited to boolean, integer and float... maybe.

XPath recovers silently from cast errors.

> It'll be something that extends RuntimeException, in this case
> IllegalArgumentException. Checked exceptions wreck my buzz :)

Although I have a different opinion on checked exceptions, I'd point
out that DOMException is a RuntimeException -- all that JavaScript
heritage shows through.

Ari.

• Follow-Ups:
  • Re: [proposal] XPath API for Java
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• References:
  • [proposal] XPath API for Java
    • From: Bill de hÓra <bill@d...>
  • Re: [proposal] XPath API for Java
    • From: ari@c... (K. Ari Krupnikov)
  • Re: [proposal] XPath API for Java
    • From: Bill de hÓra <bill.dehora@p...>

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