The Codeless Code: Case 103 The Black Enamel Box 
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 Master Bawan posed this dilemma to the developers in his
charge:

“When investigating strange behavior in the production
environment, our most powerful weapon has always been debug
messages: the more numerous and detailed, the better. Yet
when used copiously, the formatting of such messages becomes
expensive—needlessly expensive, for we exclude debug
messages from our logs when we are not investigating
problems. So which path is best? Safe but slow, or heedless
but fast?”

“Wú,” said one of the nuns. “Everything may be logged, with
minimal expense. Wrap every debug call within an if
statement which verifies that debugging is on before
bothering to format the message. We will only be slow when
we need to be safe.”

Bawan considered this, and seemed pleased. He bade the nun
implement her approach in an application that was presently
being designed. As further reward for her cleverness he
presented her with two enamel boxes.

“Open the red box immediately,” said Bawan, “but leave the
black box shut tight. In time it will serve you.”

Inside the red box the nun discovered a small bowl full of
succulent kiwi fruit, lychee, and white pears, resting on a
bed of goji berries. These she enjoyed greatly that very
evening.  Afterwards she placed both boxes on a high shelf,
and eventually forgot about them.

Two years later, after the system had undergone several
enhancements, a minor production problem appeared—the first
in many releases. The nun requested that the system be
restarted in debug mode.

Suddenly, stack traces from NullPointerExceptions appeared
on the screens of every user. The system had become
completely unusable.  As the nun stood aghast amid the
chaos, master Bawan sidled up to her and whispered, “Now
fetch the black box.”

When the lid was lifted a foul odor issued forth. Inside lay
a small bowl filled with the mouldy, dessicated remains of
what appeared to have once been kiwi fruit, lychee, pears
and goji berries.

The nun requested that debug mode be turned off and then
closed the box, enlightened.