decimal_instance_context.py

#!/usr/bin/env python


import decimal

# Set up a context with limited precision
c = decimal.getcontext().copy()
c.prec = 3

# Create our constant
pi = c.create_decimal('3.1415')

# The constant value is rounded off
print 'PI   :', pi

# The result of using the constant uses the global context
print 'RESULT:', decimal.Decimal('2.01') * pi