perl use constant

Allow declaration of constants at compile time.

use constant PI => 4 * atan2(1, 1);
use constant DEBUG => 0;

print "Pi equals ", PI, "...\n" if DEBUG;

use constant{
	SEC => 0,
	MIN => 1,
	HOUR => 2,
	MDAY => 3,
	MON => 4,
	YEAR => 5,
	WDAY => 6,
	YDAY => 7,
	ISDST => 8,
};

use constant WEEKDAYS => qw(
	Sunday Monday Tuesday Wednesday Thursday Friday Saturday
);

print "Today is ", (WEEKDAYS)[ (localtime)[WDAY]], ".\";