Class v.c.a.a.AbstractFixedPointDecimal(integer):

Part of vmc.contrib.axiom.attributes View In Hierarchy

Attribute representing a number with a specified number of decimal
places.

This is stored in SQLite as a binary integer multiplied by (10**N) where N
is the number of decimal places required by Python.  Therefore, in-database
multiplication, division, or queries which compare to integers or
fixedpointdecimals with a different number of decimal places, will not
work.  Also, you cannot store, or sum to, fixed point decimals greater than
(2**63)/(10**N).

While L{ieee754_double} is handy for representing various floating-point
numbers, such as scientific measurements, this class (and the associated
Python decimal class) is more appropriate for arithmetic on sums of money.

For more information on Python's Decimal class:

    http://www.python.org/doc/current/lib/module-decimal.html

and on general computerized Decimal math in general:

    http://www2.hursley.ibm.com/decimal/decarith.html

This is currently a private helper superclass because we cannot store
additional metadata about column types; maybe we should fix that.

@cvar decimalPlaces: the number of points of decimal precision allowed by
the storage and retrieval of this class.  *Points beyond this number
will be silently truncated to values passed into the database*, so be
sure to select a value appropriate to your application!