I'm very honored to be speaking at Dev Day 2014 in Krakow this September!
Though previously inseparable, the roommates Yíwen and Hwídah now only crossed paths occasionally, for Yíwen’s spare hours were occupied with the making of a peculiar scarf. So the restless Hwídah had taken to exploring those few parts of the Temple grounds still unknown to her.
Her wanderings led her to the halls of the abbey where dwelled the Clan of the Wolf's Bitter Breath, the black-robed monks who performed all Temple’s integration testing. Developers were forbidden to trespass in this place, though Hwídah had never been told why, and like all mysteries this one gnawed at her. She lurked in the shadows outside doorways and below cubicle partitions, hoping to learn some shocking Temple secret, but all she ever overheard from the black-robed monks within were loud jests at the expense of those developers whose code was defective. Most of these developers were of the Spider Clan, Hwídah’s own.
“It is most infuriating,” she heard one Bitter Breath monk complaining. “I have selected an Order Status of ‘Unknown’, submitted the form, and all appears well. Yet when I return to the form there is a validation error complaining of an illegal Order Status. And the developer swears that he has made no changes to this page!”
Their laughter followed Hwídah as she crept towards the abbey door. This, I shall surely investigate, she thought, her fists clenched.
Later that day Hwídah approached Java master Banzen, with the fire of righteous indignation in her eyes and a printout in her hands.
“This defect was created by a monk of the Elephant's Footprint Clan, not ours. He rewrote the method which turns each database row into an object, and his new code contains this...” Here she stabbed her finger at a line which read:
“Ah,” said Banzen. “I have seen such errors many times before. The statusCode property is Integer-valued to allow it to hold a null. But in the JDBC API, getInt returns the primitive int type and silently coerces a database NULL to a zero. This zero is silently autoboxed by setStatusCode and returned by getStatusCode when the form is populated. And since there is no Order Status of zero, a valid database row will appear to be invalid.”
“What correction for the monk of Elephant’s Footprint?” asked Hwídah.
“Nothing lethal,” said Banzen. “My usual punishment involves a boat which I keep in the south gorge for just such an occasion. The monk will emerge bruised and damp, and in the future he will examine his oars and his APIs a little more critically before using them.”
Hwídah’s face turned scarlet. “But what of the honor of Spider Clan? The monks of the Wolf’s Bitter Breath mock us openly in their abbey because of this!” Then she froze, realizing that she had revealed her trespass onto forbidden ground, but Banzen only sighed.
“The true fault lies with the authors of the venerable JDBC API, and with every maintainer since,” said the master. “They gave the monk a well-used rowboat, with sturdy oars already mounted in the oarlocks. Shall we doom him merely for not noticing that the left oar was too short? No... the dunking he receives when the boat spins in the rapids will suffice.”
Hwídah bit her lip, bowed respectfully, and turned to leave.
“Little nun,” said Banzen, raising his index finger to stop her. “The defect is not mine, and I cannot prevent the errors it engenders. Thus I use both defect and error to serve a greater purpose.”
“Banzen seems determined to suffer this same error being made until the end of time!” concluded Hwídah in exasperation. “We should give the Elephant’s Footprint a better boat!”
“Indeed!” said Satou. “When I learned of this error, I begged the master to switch to a popular ORM framework. Yet refactoring has its costs, and every tool has its perils, so the low-level code remains.”
“Then we should provide a left oar of our own!” said Hwídah.
“Indeed!” said Djishin. “When I learned of this error, I authored a suitable getInteger utility method. Yet developers will only seek out what they think they need, and what they know to look for, so the utility goes unused.”
Hwídah sank in despair. “So the monk of Elephant’s Footprint is barely corrected, and the monk of the Wolf’s Bitter Breath is not corrected at all. At least miserable Hwídah has been corrected, for now I understand why it is forbidden to enter the Wolf’s Den, and that is to maintain harmony between our clans. An insult can only become a grievance if it is overheard.”
Djishin said, “You perceive the shafts of the oars above the water, but your true course has been determined by what lies beneath.”
Satou continued, “Our master knows you violated the edict: this much he has told us freely. But the edict is not his, and he cannot prevent it from being violated by the irrepressibly curious. Thus he uses both the edict and its violations for a greater purpose.”
Satou put a companionable arm around Hwídah. “Enjoy your meal, sister of the Spider Clan! For I fear that Hwídah’s correction is just beginning...”
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