Package orm2 :: Package util :: Module fixedpoint :: Class FixedPoint

Class FixedPoint

object --+
         |
        FixedPoint

Basic FixedPoint object class,
The exact value is self.n / 10**self.p;
self.n is a long; self.p is an int

Instance Methods

[hide private]

__init__(self, value=0, precision=DEFAULT_PRECISION)
x.__init__(...) initializes x; see x.__class__.__doc__ for signature

get_precision(self)
Return the precision of this FixedPoint.

set_precision(self, precision=DEFAULT_PRECISION)
Change the precision carried by this FixedPoint to p.

__str__(self)
str(x)

__repr__(self)
repr(x)

copy(self)

__copy__(self)

__deepcopy__(self, memo)

__cmp__(self, other)

__hash__(self)
Caution! == values must have equal hashes, and a FixedPoint is essentially a rational in unnormalized form.

__nonzero__(self)
Returns true if this FixedPoint is not equal to zero...

__neg__(self)

__abs__(self)
Returns new FixedPoint containing the absolute value of this FixedPoint...

__add__(self, other)

__radd__(self, other)

__sub__(self, other)

__rsub__(self, other)

__mul__(self, other)

__rmul__(self, other)

__div__(self, other)

__rdiv__(self, other)

__divmod__(self, other)

__rdivmod__(self, other)

__mod__(self, other)

__rmod__(self, other)

__float__(self)
Return the floating point representation of this FixedPoint.

__long__(self)
EJG/DF - Should this round instead? Note e.g.

__int__(self)
Return integer value of FixedPoint object.

frac(self)
Return fractional portion as a FixedPoint.

_roundquotient(self, x, y)
...

__reduce(self)
Return n, p s.t.

round(self, dividend, divisor, quotient, remainder)
...

Inherited from object: __delattr__, __getattribute__, __new__, __reduce__, __reduce_ex__, __setattr__

Class Variables

[hide private]

__slots__ = ['n', 'p']

n = <member 'n' of 'FixedPoint' objects>

p = <member 'p' of 'FixedPoint' objects>

Properties

[hide private]

precision

Inherited from object: __class__

Method Details

[hide private]

init(self, value=0, precision=DEFAULT_PRECISION)
(Constructor)

source code

x.__init__(...) initializes x; see x.__class__.__doc__ for signature

Overrides: object.__init__: (inherited documentation)

get_precision(self)

source code

Return the precision of this FixedPoint.

The precision is the number of decimal digits carried after
the decimal point, and is an int >= 0.

set_precision(self, precision=DEFAULT_PRECISION)

source code

Change the precision carried by this FixedPoint to p.

precision must be an int >= 0, and defaults to
DEFAULT_PRECISION.

If precision is less than this FixedPoint's current precision,
information may be lost to rounding.

str(self)
(Informal representation operator)

source code

str(x)

Overrides: object.__str__: (inherited documentation)

repr(self)
(Representation operator)

source code

repr(x)

Overrides: object.__repr__: (inherited documentation)

copy(self)

source code

None

copy(self)

source code

None

deepcopy(self, memo)

source code

None

cmp(self, other)
(Comparison operator)

source code

None

hash(self)
(Hashing function)

source code

Caution!  == values must have equal hashes, and a FixedPoint
is essentially a rational in unnormalized form.  There's
really no choice here but to normalize it, so hash is
potentially expensive.
n, p = self.__reduce()

Obscurity: if the value is an exact integer, p will be 0 now,
so the hash expression reduces to hash(n).  So FixedPoints
that happen to be exact integers hash to the same things as
their int or long equivalents.  This is Good.  But if a
FixedPoint happens to have a value exactly representable as
a float, their hashes may differ.  This is a teensy bit Bad.

Overrides: object.__hash__

nonzero(self)
(Boolean test operator)

source code

Returns true if this FixedPoint is not equal to zero

neg(self)

source code

None

abs(self)

source code

Returns new FixedPoint containing the absolute value of this FixedPoint

add(self, other)
(Addition operator)

source code

None

radd(self, other)
(Right-side addition operator)

source code

None

sub(self, other)
(Subtraction operator)

source code

None

rsub(self, other)

source code

None

mul(self, other)

source code

None

rmul(self, other)

source code

None

div(self, other)

source code

None

rdiv(self, other)

source code

None

divmod(self, other)

source code

None

rdivmod(self, other)

source code

None

mod(self, other)

source code

None

rmod(self, other)

source code

None

float(self)

source code

Return the floating point representation of this FixedPoint. 
Caution! float can lose precision.

long(self)

source code

EJG/DF - Should this round instead?
Note e.g. long(-1.9) == -1L and long(1.9) == 1L in Python
Note that __int__ inherits whatever __long__ does,
     and .frac() is affected too

int(self)

source code

Return integer value of FixedPoint object.

frac(self)

source code

Return fractional portion as a FixedPoint.

x.frac() + long(x) == x

_roundquotient(self, x, y)

source code


Divide x by y,
return the result of rounding
Developers may substitute their own 'round' for custom rounding
y must be > 0

__reduce(self)

source code

Return n, p s.t. self == n/10**p and n % 10 != 0

round(self, dividend, divisor, quotient, remainder)

source code


rounding via nearest-even
increment the quotient if
     the remainder is more than half of the divisor
  or the remainder is exactly half the divisor and the quotient is odd

Class Variable Details

[hide private]

slots

None

Value:

['n', 'p']

n

None

Value:

<member 'n' of 'FixedPoint' objects>

p

None

Value:

<member 'p' of 'FixedPoint' objects>

Property Details

[hide private]

precision

None

Get Method:: orm2.util.fixedpoint.FixedPoint.get_precision(self) - Return the precision of this FixedPoint.

Set Method:: orm2.util.fixedpoint.FixedPoint.set_precision(self, precision=DEFAULT_PRECISION) - Change the precision carried by this FixedPoint to p.

Delete Method:

None

Class FixedPoint

__init__(self, value=0, precision=DEFAULT_PRECISION) (Constructor)

get_precision(self)

set_precision(self, precision=DEFAULT_PRECISION)

__str__(self) (Informal representation operator)

__repr__(self) (Representation operator)

copy(self)

__copy__(self)

__deepcopy__(self, memo)

__cmp__(self, other) (Comparison operator)

__hash__(self) (Hashing function)

__nonzero__(self) (Boolean test operator)

__neg__(self)

__abs__(self)

__add__(self, other) (Addition operator)

__radd__(self, other) (Right-side addition operator)

__sub__(self, other) (Subtraction operator)

__rsub__(self, other)

__mul__(self, other)

__rmul__(self, other)

__div__(self, other)

__rdiv__(self, other)

__divmod__(self, other)

__rdivmod__(self, other)

__mod__(self, other)

__rmod__(self, other)

__float__(self)

__long__(self)

__int__(self)

frac(self)

_roundquotient(self, x, y)

__reduce(self)

round(self, dividend, divisor, quotient, remainder)

__slots__

n

p

precision

init(self, value=0, precision=DEFAULT_PRECISION)
(Constructor)

str(self)
(Informal representation operator)

repr(self)
(Representation operator)

copy(self)

deepcopy(self, memo)

cmp(self, other)
(Comparison operator)

hash(self)
(Hashing function)

nonzero(self)
(Boolean test operator)

neg(self)

abs(self)

add(self, other)
(Addition operator)

radd(self, other)
(Right-side addition operator)

sub(self, other)
(Subtraction operator)

rsub(self, other)

mul(self, other)

rmul(self, other)

div(self, other)

rdiv(self, other)

divmod(self, other)

rdivmod(self, other)

mod(self, other)

rmod(self, other)

float(self)

long(self)

int(self)

slots