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Re: [xml-dev] Preoccupation with zero, empty strings, empty elements,empty everything

To my mind the treatment of zero in xml falls under the category of 'implication'.
Sometimes you need to send xml documents that are fully normalized (in the xml sense); other times you just need send deltas from some common assumed ur-document; perhaps most frequently, something in the middle is sent: too much information to be terse but not enough to be standalone.


On 08/12/2013 12:35 AM, "Costello, Roger L." <costello@mitre.org> wrote:
Hi Folks,

When was the last time you went to the store to purchase zero oranges?

When was the last time you created an XML document to have zero elements?

Those are strange concepts, aren't they?

Zero is a strange concept.

Roughly 1500 years after the introduction of zero as a number by mathematicians in India, the concept is still not well accepted in computer science:

        - Many programming languages do not
          support records with zero fields

        - Many programming languages do not
          support arrays with zero elements

        - Many programming languages do not
          support variable definitions with zero

        - In some programming languages the
          syntax for calling a routine with zero
          parameters differs from that for a
          routine with one or more parameters

        - XML has a special syntax for empty

        - Many compilers refuse to compile a
          module that defines zero names

        - No parser generator can produce a
          parser for the empty language (the
          language with zero strings)

This preoccupation with empty strings, sets, languages, etc. is not frivolous, since it is well-known that the ease with which a system handles empty cases is a measure of its cleanliness and robustness.

Most (not all) of the above is from the book: "Parsing Techniques" by Grune and Jacobs.



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