Kōans for the Software Engineer -- An illustrated collection of (sometimes violent) fables, concerning the Art and Philosophy of software development.
The nun Hwídah has composed this uncharacteristically somber sonnet for your contemplation: I chanced upon an ancient cache of code: a stack of printouts, tall as any man, that in decaying boxes had been stowed. Ten thousand crumbling pages long it ran. Abandoned in the blackness to erode, what steered a ship through blackness to the moon. The language is unused in this late year. The target…
Two monks were arguing about the best way to implement two somewhat-similar workflows in their application. They went to the visiting master Suku to settle their dispute. The first monk said, “I believe we should implement both workflows separately to keep them from constraining each other. When all work is done we can identify the common parts, and combine them into generic base classes or…
For years the young monk Djishin had been apprenticed to old master Banzen. Although this was a privilege it brought Djishin little joy, for lately the master had been growing visibly irritated with the young monk. Yet the monk could not fathom the reason. One morning Djishin said to his fellow apprentice Satou: I have committed Banzen’s teachings to heart and perform my duties according to his…
The head monk of the Swooping Falcon Clan asked master Banzen for assistance with a difficult customer. The customer was a maker of silk-and-bamboo kites, and the clan’s application allowed her to curate her large online catalog. “I simply cannot make her happy,” complained the head monk. “Tell me what makes her unhappy,” said Banzen. “Then perhaps you can do the opposite of that.” “Laziness,” the…
The Hungry Worm Clan was building a website for a craftsman who made custom farming tools. Young master Zjing was reviewing the code of their three developers. “I do not understand the purpose of the LatestSellByDate property in your shopping cart’s PurchaseItem ,” she said to the three. “Shovels and rakes do not expire.” “That property was requested by the Red Pebble Clan,” replied the first…
A certain monk heard that master Suku knew the secret of designing code for maximum reusability. But whenever the monk begged the master to share her wisdom, Suku only walked away. Exasperated, the monk asked one of Suku’s three apprentices for help. “To learn the master’s great secret, you must approach her correctly,” explained the apprentice. “Come; I shall assist you.” The apprentice gave the…
After one of master Kaimu’s lectures, a monk approached the master and said: I am bored of this endless talk of coding practices, of tools and techniques. It is said you know much about artificial intelligence—say something about that. Kaimu grabbed the monk in a headlock, held a knife to his ear, and said: Let me cut away these useless appendages, that you might see more clearly. When the…
Now that the Temple had adopted the Agile Way, its analysts, developers, and testers had been reorganized into many Tiny Clans. Each Tiny Clan had been given the freedom to develop its applications in whatever manner it saw fit. It was still the task of the masters to review the code of all, though their authority had been much diminished. Thus it was with no great joy that young master Zjing…
On the Monday after the first budding of spring, the entire Temple was called to assembly in the Great Hall by old Madame Jinyu, the Abbess Over All Clans And Concerns. Not a single person was excused—indeed, two desperately ill monks were carried in on stretchers and hoisted upright against the back wall, next to the propped-up corpse of a senior nun who had died the previous Thursday…
The nun Hwídah was eating lunch with her clan when a senior monk approached, seeking her aid with a production issue. Not wishing to disturb the others, the senior monk bent down to whisper in Hwídah’s ear. “Ah,” said Hwídah, rising from the table. “The three most terrifying words.” Immediately she departed with the senior monk. A novice who witnessed this exchange happened upon the senior monk…
While passing by the temple’s Support Desk, the nun Hwídah heard of strange behavior in a certain application. Since she had been appointed by master Banzen to assist with production issues, the nun dutifully described the symptoms to the application’s senior monk: “Occasionally a user will return to a record they had previously edited, only to discover that some information is missing,” said…
As punishment for implementing an unusual solution to a problem, the nun Satou had been ordered by master Banzen to pose motionless in the entryway of his office each day, pretending to be a coat stand. Each new visitor that entered would invariably look about with puzzlement and ask what should be done with their coat. The master would then point wordlessly to Satou. Eventually the visitor would…
After the nun Satou had corrected her code, she returned to Java master Banzen and asked that he review it. “So,” said Banzen, squinting at the latest revision. “You now obtain your ‘hash of the pages contents’ by taking the byte-array that holds those contents and sending it into Arrays.hashCode() .” “Will that not work?” asked Satou nervously. “It will function adequately in this circumstance,”…
Java master Banzen was reviewing the code of a web application when he came across a new HTTP filter authored by his apprentice Satou. The old master called her to his office. “You have begun including an ‘ETag’ header with each page you send,” said Banzen to the nun. “Explain, for I have not heard of this header.” “The ETag is a hash of the page contents,” said Satou with pride, glad to know…
A junior monk said to master Kaimu: One of the Patriarchs claimed that there are “only two hard things” in our craft. What are these “two hard things”? Kaimu answered: You only need to remember that the first hard thing is called “cache invalidation”. The junior monk asked: Does that mean that a whole cache is made invalid, or just some of its elements? And why call it “invalidation” when the only…