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From Christian Sell <christian.s...@netcologne.de>
Subject Re: [Jelly] restrict use of tag libraries
Date Tue, 04 Feb 2003 14:02:55 GMT
James Strachan wrote:
> There's a few ways this could go. We could add a mechanism so that Tag
> libraries could restrict the use of other libraries within themselves. e.g.
> a specific TagLibrary could dsiable or enable some/all libraries from being
> usable within one/all of its tags.
> 
> Another option could be for an individual tag to validate its body inside
> the doTag() method. By calling getBody() and then traversing the tree of
> TagScripts, a specific Tag could validate that the body does not contain
> dynamic expressions or Tags of certain kinds etc.
> 
> The latter would be pretty easy to implement in your specific example I
> think. We could maybe provide some kind of helper class (TagWalker?) to aid
> Tag implementors wishing to traverse over their bodies, validating child
> tags.

both seem useful. However, in my case, where I dont want any scripting 
at all, I could also call getParent() from within my element2, and 
assert that the class is that of element1, right?

In general, I have the feeling that it would be nice if we could 
delegate more error checking and validation into the runtime, based on 
declarations provided by the taglib - instead of having to perform it in 
every tag implementation (or not at all).

> 
> James
> -------
> http://radio.weblogs.com/0112098/
> ----- Original Message -----
> From: "Christian Sell" <christian.sell@netcologne.de>
> To: "Jakarta Commons Users List" <commons-user@jakarta.apache.org>
> Sent: Monday, February 03, 2003 9:51 PM
> Subject: Re: [Jelly] restrict use of tag libraries
> 
> 
> Paul Libbrecht wrote:
> 
>>Christian,
>>
>>What do you mean by "no taglibs allowed here" ?
> 
> 
> I mean that writing
> 
> <element1 xmlns="com.yadda.Yadda">
> 
> *will* go through, but writing
> 
> <element1 xmlns="com.yadda.Yadda" xmlns:y="core">
> 
> will *not* go through. In fact, what I really want is to make sure that
> there is no scripting from other taglibs between my element1 and
> element2 - the namespaces are not really the problem.
> 
> <
> 
>>Do you mean no taglib-declaration ?
>>Do you mean only the following taglibs' tags ?
>>
>>In both cases, this has to do with parsing. So a schema, as James
>>mentionned, or some other (e.g. forcing a SAX filter between the parser
>>and the jelly document-handler).
> 
> 
> I still dont see what role a "schema" would play here
> 
> 
>>Remember: jelly scripts are first parsed then executed (possibly several
>>times).
>>Hope it helps.
>>
>>Paul
>>
>>
>>Le Lundi, 3 févr 2003, à 19:35 Europe/Berlin, Christian Sell a écrit :
>>
>>
>>><element1 xmlns="com.yadda.Yadda"> <!-- no taglibs allowed here -->
>>>    <element2 xmlns:j="jelly:core" xmlns:log="jelly:log">
>>>        <j:something/>
>>>        .....
>>>    </mytags:element2>
>>></mytags:element1>
>>
>>
>>
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> 
> 
> 
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