VII.1 Reuse

子日,述而不作,信而好古,窃比于我老彭. – 论语 七:一

The Master said, ‘I transmit but do not innovate; I am truthful in what I say and devoted to antiquity. I venture to compare myself to your Old P’eng.’ – Analects VII.1 (Lau)

Before contemplating the process implications of this radically static statement, let’s note that from the perspective of designed code itself, it is always true. Code transforms and transmits information. This is the garbage-in garbage-out principle. Designed code (not genetic or evolved code) does not innovate.

Backups of the user directory for the Analects’ source control repository are, alas, lost to antiquity, and though many sophisticated data recovery techniques have been tried, with some success, none have yielded the identity of Old P’eng. Our ignorance of him highlights our relationship with Confucius and with any classical tradition. To us, Confucius founded a philosophical school, but in his own words he merely continued a tradition that we can see indirectly, if at all.

Scholarly consensus is that Confucius is deliberately overstating his lack of innovation for reasons of rhetoric or modesty (see eg DC Lau, AC Graham, or just wikipedia on this verse). Nevertheless the verse is considered pivotal in understanding Confucius’ traditionalism and conservatism in a time of extraordinary violence and social change.

Existing solutions are useful in at least two ways. 

Firstly they may capture unintuitive theoretical results in accessible ways. Many algorithm design and data structure results are now in this category, such as sorting algorithms and efficient concurrent maps (eg the Java 6 lock free implementation of java.util.ConcurrentHashMap). The formal scientific characterization of such solutions in terms of, say, algorithmic complexity and performance benchmarks  make computer theoretic literacy crucial. Programmers will be unlikely to understand the derivation by reading the code, so they must be able to read the documentation. 

Secondly they may capture highly specific details of the environment and robust solutions to managing it. This will include successful workarounds for under-specified elements of protocols, or flat-out incorrect but popular implementations. Any user of say Ruby on Rails or Tomcat takes advantage of this kind of reuse. Consider too the domain specific details and tolerances of a fly-by-wire control system for a particular make and model of plane.

These two kinds of reuse may be contrived to lie on a spectrum, but I’ve chosen to distinguish them here for their correspondence to two different categories of knowledge – logos and metis. In classical Greek epistemology logos is theoretic universal knowledge and metis is hard won cunning, “feel”, or craft knowledge (as an aspect of techne, craft knowledge and theory). James C. Scott describes the Greek hero Odysseus, surgeons and maritime pilots as all relying on metis (Seeing Like A State). Scott also makes the connection between traditional knowledge – which is particular and tied to a society and geography – and common law conservatism in the tradition of Edmund Burke and Michael Oakeshott.

Confucius is claimed as a kind of Burkean conservative, for instance, by James Kalb. Both Confucius and Burke grew up in societies with small literate elites and large impoverished peasantries. They both share senses of the worth of settled convention, the importance of teaching and the literary canon, a paternalistic affection for heredity power, and a sympathy for the welfare of everyday people.  Neither are they reactionaries, but welcome improvement at a humane pace (IX.3).

Seeing Burke and Confucius as similar is not mainstream and deserves a dedicated analysis of its own. (My searches revealed more extant work linking both of them individually to Wittgenstein than to each other, but pointers are always welcome.) In a comprehensive entry for Burke in the Stanford Encyclopedia of Philosophy, Ian Harris argues that despite being more often claimed by the right wing, he does not have a clear modern partisan successor. Nevertheless, distinguished scholars like DC Lau or AC Graham stay well clear of Western political comparisons, while happily comparing classical Chinese figures with Western philosophers. 

Unusually, a software library, and all the hard won craft knowledge that comes with it, can be imported into another with extraordinary ease when compared to other forms of craft knowledge. A pilot is of little advantage outside his home port, and Ruby on Rails is of little use for 3D rendering, but in software we can copy the pilot and use him on innumerable ships entering that port. We can also ultimately read the source code to Ruby on Rails and determine how it tolerates the idiosyncrasies of particular browsers and servers. This is because all code is built on a formal information substrate – the computational medium. (This is Harrison Ainsworth’s term and his note on reuse provided a number of the connections in this post.)

Not all craft knowledge of a codebase is encapsulated in the codebase. There are particularities of the install, workaround scripts, configuration, scheduled jobs and so on, but these are ultimately digital artifacts easily included within a slightly broader view of what a codebase is (this latter is a premise of DevOps and for anyone serious about a controlled environment). More problematically, there are conventions of use, design choices, oral traditions of “check here when you change there”, and so on. At the limit, all codebases are incomplete. They depend on co-texts, results and knowledge of the domain that need not be encoded. An air traffic control system does not need a textbook description of Bernoulli’s Principle.

Burke and Scott argue that in an established society important, non-obvious, traditional knowledge is captured in social conventions and established practice, and the practice cannot be simplified without a loss of valuable situational knowledge. Scott additionally points out that such an environment is very difficult for an outsider to navigate and there are strong motivations for central political power to apply simplifications to it.

Yet highly particular, ‘local’ code that requires hands on experience and knowledge of accompanying conventions most frequently has another name in software development: bad. Or: spaghetti. Or: legacy. The sentiment is well captured in Qi’s koan on fear, even if it does riff off an opposing classical Chinese tradition. (In Confucian terms we might note the building is not harmonious.)

In No Silver Bullet, Brooks distinguishes accidental and inherent complexity, with the latter being an attribute of the underlying problem rather than any specific software or hardware implementation. Complexity due to poor or improvable design is always accidental; that due to the problem domain is by definition inherent.

An aesthetic sense of good or poor design becomes crucial when pursuing aggressive reuse (VII.14). Without it you will simply perpetuate junk.

Having argued the link between conservatism and software reuse, it is worth being a little more precise about flavours of conservatism. William F. Buckley famously described it as that which “stands athwart history, yelling Stop, at a time when no one is inclined to do so, or to have much patience with those who so urge it.” Despite its partisan origins, this is a good start, as it illustrates certain threads of environmentalism and the idea of heritage listing fall easily under the same banner. ((It is also useful to think of contemporary US Democrats defending Franklin D. Roosevelt’s New Deal, or opposition to changes to Britain’s NHS in this frame.))

In its purest form, this can be “return to a golden age” conservatism. There’s certainly an argument that Confucius would have been happy with a reversion to the society of the Eastern Zhou. We should again temper our interpretation by wondering how much is rhetoric covering adaptation of tradition to new times. In software, certainly, simply reactionary approaches are of little use. Brooks and the founders of eXtreme Programming have both noted that a more effective strategy is to embrace change. Oakeshott argues in On Being Conservative that settings of widespread and enthusiastic change are in particular need of an awareness of the value of what exists now. A traditionalist most often defends the present versus the future, not the past versus the present. This conservative disposition’s usefulness to software is more apparent if taken as an analytic tool rather than an inherent aspect of personality. After all, the greenfield doesn’t exist (see X.18), and any project that pretends to be a greenfield is an interesting lie.

Conservative thought in this vein usually emphasizes working within a tradition and a community – in software we would say platform. This also suggests interesting contours for the breadth of possible reuse; and there are other verses, such as XVI.11, where that might be explored. What is immediately apparent is the narrowness and fragility of an entirely in-house platform due to the smallness of its developer community; and the need for a shared jargon (XIII.3) and perhaps a canon (XVI.13).

Given the corpus of extant code in the form of libraries, to adore antiquity is to know your platform, including its innards, not just thoughtless rote quoting via copy and paste. At this moment in software, to reuse and extend is a greater service than extraneous self-involvement masquerading as innovation.

If you can easily find some code and copy it, you get the result at zero cost. That is an efficiency that cannot be beaten: no amount of programming tool and technique improvements can ever do that. So we want to maximise reuse. – Fred Brooks, No Silver Bullet


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