Re: [Jsdsi-users] extending jsdsi.Tag

[Guillermo N. <gna...@cc...>]

Sameer Ajmani <aj...@cs...> writes:

> Would making toTagSexp() protected solve your problem?  We can probably do
> this.

yes, it will be perfect. 

I think it will allow others to provide specific tags with their own
intersect() methods without modifying the jsdsi package by extending
Tag. (again, I don't know if it is a good practice or if it should be
allowed, but at least i find it useful).


guillermo

>
> Sameer
>
>>
>> Thanks a lot for the answer and the advice,
>>
>>> To construct application-specific tags, just use the Tag subclasses.
>>
>> I wanted to create a new Tag object because the semantics of my
>> authorization tag require a different intersect() function. I just
>> though that I could extend jsdsi.Tag implementing the abstract
>> methods, and providing my own intersect algorithm for my specific tag.
>>
>> If I implement my own Tag extending jsdsi.Tag I get an error because I
>> cannot implement the abstract method Tag.toTagSexp(). Making it public
>> in Tag solves the error, although I don't know if this is a good
>> practice.
>>
>> Thanks again,
>>
>> Guillermo
>>
>>
>> Sameer Ajmani <aj...@cs...> writes:
>>
>>> Tag.toSexp() returns (tag <tag-material>), while Tag.toTagSexp() just
>>> returns <tag-material>.  This just matters for when you write tags to
>>> a file or to the network (you should always use toSexp(), so that the
>>> receiver knows that it's getting a Tag).  To construct
>>> application-specific tags, just use the Tag subclasses.  For example,
>>> a tag like this:
>>> (tag (file (*set read write) (*prefix /home/ajmani)))
>>> Is constructed as:
>>> new SimpleTag("file",
>>>   new ExprTag[] {
>>>     new SetTag(new ExprTag[] { new StringTag("read"),
>>>                                new StringTag("write") }),
>>>     new PrefixTag("/home/ajmani");
>>>   };
>>> ).toSexp();
>>>
>>> or parse the original string into an object:
>>>
>>> Tag myTag = (Tag)Obj.parseObj
>>> (new SexpInputString
>>> (new ByteArrayInputStream
>>> (Sexp.encodeString
>>> ("(tag (file (*set read write) (*prefix /home/ajmani)))")
>>> )).readSexp());
>>>
>>> Sameer
>>>
>>>> Hi,
>>>>
>>>> I have a little question regarding jsdsi.Tag. I need to create an
>>>> application specific Tag and I was wondering if the abstract class
>>>> Tag is intended to be extended by external sw packages.
>>>>
>>>> If this is the case, the method Tag.toTagSexp() shouldn't it be
>>>> declared public or protected? In the latests stable version and
>>>> current CVS version is is package-private. And if this is not the
>>>> case, which is the best way to implement an application-specific tag?
>>>>
>>>>
>>>> thanks,
>>>>
>>>> Guillermo
>>>>
>>>> --
>>>> ---------------------------------------------------------------
>>>> Guillermo Navarro (gna...@cc...)
>>>> Phone: +34 93 581 3577
>>>> FAX: +34 93 581 3033
>>>> Home: http://www.ccd.uab.es/~guille
>>>> Combinatoria i Comunicacio Digital (http://www.ccd.uab.es)
>>>> Universitat Autonoma de Barcelona  - 08193 Bellaterra, Spain
>>>> ---------------------------------------------------------------
>>>>
>>>>
>>>>
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>>>
>>>
>>> http://ajmani.net
>>>
>>>
>>>
>>>
>>>
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>>
>> --
>> ---------------------------------------------------------------
>> Guillermo Navarro (gna...@cc...)
>> Phone: +34 93 581 3577
>> FAX: +34 93 581 3033
>> Home: http://www.ccd.uab.es/~guille
>> Combinatoria i Comunicacio Digital (http://www.ccd.uab.es)
>> Universitat Autonoma de Barcelona  - 08193 Bellaterra, Spain
>> ---------------------------------------------------------------
>
>
> http://ajmani.net
>
>
>

-- 
---------------------------------------------------------------
Guillermo Navarro (gna...@cc...)    
Phone: +34 93 581 3577
FAX: +34 93 581 3033
Home: http://www.ccd.uab.es/~guille
Combinatoria i Comunicacio Digital (http://www.ccd.uab.es)
Universitat Autonoma de Barcelona  - 08193 Bellaterra, Spain
---------------------------------------------------------------