RE: The XML abstraction leaks

Thank you David and Michael. I would like to follow up please.

I really am fascinated by the topic of abstractions and leaky abstractions. I hope that lots of people will pitch in with their thoughts and opinions on this topic.

1. What is “the XML abstraction”? I said that it is this:

An XML document contains data and the data
               is surrounded (delimited) by markers. More
               concretely, an XML document contains pairs
               of start-tags and end-tags, sandwiched between
               them is character data and possibly other
               start-tag, end-tag pairs.

Do you agree that that is the XML abstraction? If not, would you provide your definition of “the XML abstraction” please?

2. What is a “leaky abstraction”? From reading Joel Spolsky’s article as well as Peter Seibel’s description [1] I have arrived at this definition:

               The XML abstraction leaks when users must
               understand to some extent how software that
               implements the XML abstraction—the XML
               processor—works internally.

Do you agree with that? If not, would you provide your definition of what it means for the XML abstraction to leak please?

3. Would you identify a leak in the XML abstraction please?

/Roger

[1] Peter Seibel has a wonderful discussion of leaky abstractions in his book, Practical Common Lisp. He gives an awesome example of a user-defined function (abstraction) that leaks.