The Escape of a Small Program
C. A. R. Hoare's Law of Large Programs states that inside every large program is a small program struggling to get out. The parking receipt I got yesterday returning from a SQO-OSS meeting proves this fact.
It looks like a printf formatting specification was doubly
escaped, or used outside the context of a printf statement.
As a result, the "PERSONELL" [sic] value in the receipt contains,
instead of an actual value,
the printf decimal escape sequence %d .
Maybe, because no person is associated with the receipt, the car's plate
number is also wrong.
Why do I claim that the two characters "%d" form a small program?
If you think of it, the
printf
formatting specifications are a small, domain-specific language.
They allow us to format fixed-width fields, creating report-like
output records.
Carelessly written
printf statements can even be abused by mallicious code
to inject abritrary code into a program.
Finally, this small and cryptic language has been so successful that
it is now part of Java 1.5 in the Formatter class.
