author’s Response:

As Williams says, the topic of my article was not interpreting preserved bits. Jeff Rothenberg drew attention to the threat of format obsolescence in scientific american (Jan. 1995), a focus that has dominated digital preservation ever since. Rothenberg was writing before the Gutenberg-like impact of the Web transformed digital formats from private, to applications, to publishing medium, leading him and others to greatly overestimate the obsolescence risk of current formats.

I am unable to identify a single format widely used in 1995 that has since become obsolete but would welcome an example. At the 2010 iPres conference (http:// www.ifs.tuwien.ac.at/dp/ipres2010/) I asked the audience whether any of them had ever been forced to migrate the format of preserved content to maintain renderability, and no one had.

Format obsolescence is clearly a threat that must be considered, but compared to the technical and economic threats facing the bits we generate, it is insignificant and the resources devoted to it are disproportionate.

David s.h. Rosenthal, Palo alto, Ca

def quicksort(v) return v if v.nil? or v.length <= 1 less, more = v[ 1..- 1]. partition { |i| i < v[0] } quicksort(less) + [v[0]] + quicksort(more)

end

objects always! Well,
almost always

Unlike Mordechai Ben-Ari’s Viewpoint “Objects Never, Well, Hardly Ever!” (Sept. 2010), for me learning OOP was exciting when I was an undergraduate almost 30 years ago. I realized that programming is really a modeling exercise and the best models reduce the communication gap between computer and customer. OOP provides more tools and techniques for building good models than any other programming paradigm.

Viewing OOP from a modeling perspective makes me question Ben-Ari’s choice of examples. Why would anyone expect the example of a car to be applicable to a real-time control system in a car? The same applies to the “ interface” problem in supplying brake systems to two different customers. There would then be no need to change the “interface” to the internal control systems, contrary to Ben-Ari’s position.

Consider, too, quicksort as imple-
mented in Ruby:
This concise implementation shows
quicksort’s intent beautifully. Can a
nicer solution be developed in a non-
OOP language? Perhaps, but only in a
functional one. Also interesting is to
compare this solution with those in 30+
other languages at http://en.wikibooks.
org/wiki/Algorithm_implementation/
Sorting/Quicksort, especially the Java
versions. OO languages are not all cre-
ated equal.

ing trap that often permeates this debate. OO offers a higher level of encapsulation than non-OO languages and allows programmers to view software realistically from a domain-oriented perspective, as opposed to a solution/ machine-oriented perspective.

The notion of higher levels of encapsulation has indeed permeated many aspects of programmer thinking; for example, mobile-device and Web-ap-plication-development frameworks leverage these ideas, and the core tenets of OO were envisioned to solve problems involving software development prevalent at that time.

Helping my students become competent, proficient software developers, I find the ones in my introductory class move more easily from OOP-centric view to procedural view than in the opposite direction, but both types of experience are necessary, along with others (such as scripting). So, for me, how to start them off and what to emphasize are important questions. I like objects-first, domain-realistic software models, moving as needed into the nitty-gritty (such as embedded network protocols and bus signals). Today’s OO languages may indeed reflect deficiencies, but returning to an environment with less encapsulation would mean throwing out the baby with the bathwater.

James B. fenwick Jr., boone, nC

I respect Mordechai Ben-Ari’s View-
point (Sept. 2010), agreeing there is
neither a “most successful” way of
structuring software nor even a “domi-
nant” way. I also agree that research
into success and failure would inform
the argument. However, he seemed to
have fallen into the same all-or-noth-
The bells rang out as I read Morde-
chai Ben-Ari’s Viewpoint (Sept. 2010)—
the rare, good kind, signaling I might
be reading something of lasting im-
portance. In particular, his example of
an interpreter being “nicer” as a case/
switch statement; some software is
simply action-oriented and does not fit
the object paradigm.

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