Made the various is_* operations return booleans. This was discussed
with Cawlishaw by mail, and he basically confirmed that to these is_*
operations, there's no need to return Decimal(0) and Decimal(1) if
the language supports the False and True booleans.
Also added a few tests for the these functions in extra.decTest, since
they are mostly untested (apart from the doctests).
Thanks Mark Dickinson
diff --git a/Lib/decimal.py b/Lib/decimal.py
index 6ca8bab..4017e82 100644
--- a/Lib/decimal.py
+++ b/Lib/decimal.py
@@ -679,14 +679,11 @@
return 0
def __nonzero__(self):
- """Is the number non-zero?
+ """Return True if self is nonzero; otherwise return False.
- 0 if self == 0
- 1 if self != 0
+ NaNs and infinities are considered nonzero.
"""
- if self._is_special:
- return True
- return sum(self._int) != 0
+ return self._is_special or self._int[0] != 0
def __cmp__(self, other):
other = _convert_other(other)
@@ -2239,15 +2236,18 @@
return ans
def same_quantum(self, other):
- """Test whether self and other have the same exponent.
+ """Return True if self and other have the same exponent; otherwise
+ return False.
- same as self._exp == other._exp, except NaN == sNaN
+ If either operand is a special value, the following rules are used:
+ * return True if both operands are infinities
+ * return True if both operands are NaNs
+ * otherwise, return False.
"""
+ other = _convert_other(other, raiseit=True)
if self._is_special or other._is_special:
- if self._isnan() or other._isnan():
- return self._isnan() and other._isnan() and True
- if self._isinfinity() or other._isinfinity():
- return self._isinfinity() and other._isinfinity() and True
+ return (self.is_nan() and other.is_nan() or
+ self.is_infinite() and other.is_infinite())
return self._exp == other._exp
def _rescale(self, exp, rounding):
@@ -2730,84 +2730,60 @@
return ans
def is_canonical(self):
- """Returns 1 if self is canonical; otherwise returns 0."""
- return Dec_p1
+ """Return True if self is canonical; otherwise return False.
+
+ Currently, the encoding of a Decimal instance is always
+ canonical, so this method returns True for any Decimal.
+ """
+ return True
def is_finite(self):
- """Returns 1 if self is finite, otherwise returns 0.
+ """Return True if self is finite; otherwise return False.
- For it to be finite, it must be neither infinite nor a NaN.
+ A Decimal instance is considered finite if it is neither
+ infinite nor a NaN.
"""
- if self._is_special:
- return Dec_0
- else:
- return Dec_p1
+ return not self._is_special
def is_infinite(self):
- """Returns 1 if self is an Infinite, otherwise returns 0."""
- if self._isinfinity():
- return Dec_p1
- else:
- return Dec_0
+ """Return True if self is infinite; otherwise return False."""
+ return self._exp == 'F'
def is_nan(self):
- """Returns 1 if self is qNaN or sNaN, otherwise returns 0."""
- if self._isnan():
- return Dec_p1
- else:
- return Dec_0
+ """Return True if self is a qNaN or sNaN; otherwise return False."""
+ return self._exp in ('n', 'N')
def is_normal(self, context=None):
- """Returns 1 if self is a normal number, otherwise returns 0."""
- if self._is_special:
- return Dec_0
- if not self:
- return Dec_0
+ """Return True if self is a normal number; otherwise return False."""
+ if self._is_special or not self:
+ return False
if context is None:
context = getcontext()
- if context.Emin <= self.adjusted() <= context.Emax:
- return Dec_p1
- else:
- return Dec_0
+ return context.Emin <= self.adjusted() <= context.Emax
def is_qnan(self):
- """Returns 1 if self is a quiet NaN, otherwise returns 0."""
- if self._isnan() == 1:
- return Dec_p1
- else:
- return Dec_0
+ """Return True if self is a quiet NaN; otherwise return False."""
+ return self._exp == 'n'
def is_signed(self):
- """Returns 1 if self is negative, otherwise returns 0."""
- return Decimal(self._sign)
+ """Return True if self is negative; otherwise return False."""
+ return self._sign == 1
def is_snan(self):
- """Returns 1 if self is a signaling NaN, otherwise returns 0."""
- if self._isnan() == 2:
- return Dec_p1
- else:
- return Dec_0
+ """Return True if self is a signaling NaN; otherwise return False."""
+ return self._exp == 'N'
def is_subnormal(self, context=None):
- """Returns 1 if self is subnormal, otherwise returns 0."""
- if self._is_special:
- return Dec_0
- if not self:
- return Dec_0
+ """Return True if self is subnormal; otherwise return False."""
+ if self._is_special or not self:
+ return False
if context is None:
context = getcontext()
-
- r = self._exp + len(self._int)
- if r <= context.Emin:
- return Dec_p1
- return Dec_0
+ return self.adjusted() < context.Emin
def is_zero(self):
- """Returns 1 if self is a zero, otherwise returns 0."""
- if self:
- return Dec_0
- else:
- return Dec_p1
+ """Return True if self is a zero; otherwise return False."""
+ return not self._is_special and self._int[0] == 0
def _ln_exp_bound(self):
"""Compute a lower bound for the adjusted exponent of self.ln().
@@ -3871,138 +3847,145 @@
return a.fma(b, c, context=self)
def is_canonical(self, a):
- """Returns 1 if the operand is canonical; otherwise returns 0.
+ """Return True if the operand is canonical; otherwise return False.
+
+ Currently, the encoding of a Decimal instance is always
+ canonical, so this method returns True for any Decimal.
>>> ExtendedContext.is_canonical(Decimal('2.50'))
- Decimal("1")
+ True
"""
- return Dec_p1
+ return a.is_canonical()
def is_finite(self, a):
- """Returns 1 if the operand is finite, otherwise returns 0.
+ """Return True if the operand is finite; otherwise return False.
- For it to be finite, it must be neither infinite nor a NaN.
+ A Decimal instance is considered finite if it is neither
+ infinite nor a NaN.
>>> ExtendedContext.is_finite(Decimal('2.50'))
- Decimal("1")
+ True
>>> ExtendedContext.is_finite(Decimal('-0.3'))
- Decimal("1")
+ True
>>> ExtendedContext.is_finite(Decimal('0'))
- Decimal("1")
+ True
>>> ExtendedContext.is_finite(Decimal('Inf'))
- Decimal("0")
+ False
>>> ExtendedContext.is_finite(Decimal('NaN'))
- Decimal("0")
+ False
"""
return a.is_finite()
def is_infinite(self, a):
- """Returns 1 if the operand is an Infinite, otherwise returns 0.
+ """Return True if the operand is infinite; otherwise return False.
>>> ExtendedContext.is_infinite(Decimal('2.50'))
- Decimal("0")
+ False
>>> ExtendedContext.is_infinite(Decimal('-Inf'))
- Decimal("1")
+ True
>>> ExtendedContext.is_infinite(Decimal('NaN'))
- Decimal("0")
+ False
"""
return a.is_infinite()
def is_nan(self, a):
- """Returns 1 if the operand is qNaN or sNaN, otherwise returns 0.
+ """Return True if the operand is a qNaN or sNaN;
+ otherwise return False.
>>> ExtendedContext.is_nan(Decimal('2.50'))
- Decimal("0")
+ False
>>> ExtendedContext.is_nan(Decimal('NaN'))
- Decimal("1")
+ True
>>> ExtendedContext.is_nan(Decimal('-sNaN'))
- Decimal("1")
+ True
"""
return a.is_nan()
def is_normal(self, a):
- """Returns 1 if the operand is a normal number, otherwise returns 0.
+ """Return True if the operand is a normal number;
+ otherwise return False.
>>> c = ExtendedContext.copy()
>>> c.Emin = -999
>>> c.Emax = 999
>>> c.is_normal(Decimal('2.50'))
- Decimal("1")
+ True
>>> c.is_normal(Decimal('0.1E-999'))
- Decimal("0")
+ False
>>> c.is_normal(Decimal('0.00'))
- Decimal("0")
+ False
>>> c.is_normal(Decimal('-Inf'))
- Decimal("0")
+ False
>>> c.is_normal(Decimal('NaN'))
- Decimal("0")
+ False
"""
return a.is_normal(context=self)
def is_qnan(self, a):
- """Returns 1 if the operand is a quiet NaN, otherwise returns 0.
+ """Return True if the operand is a quiet NaN; otherwise return False.
>>> ExtendedContext.is_qnan(Decimal('2.50'))
- Decimal("0")
+ False
>>> ExtendedContext.is_qnan(Decimal('NaN'))
- Decimal("1")
+ True
>>> ExtendedContext.is_qnan(Decimal('sNaN'))
- Decimal("0")
+ False
"""
return a.is_qnan()
def is_signed(self, a):
- """Returns 1 if the operand is negative, otherwise returns 0.
+ """Return True if the operand is negative; otherwise return False.
>>> ExtendedContext.is_signed(Decimal('2.50'))
- Decimal("0")
+ False
>>> ExtendedContext.is_signed(Decimal('-12'))
- Decimal("1")
+ True
>>> ExtendedContext.is_signed(Decimal('-0'))
- Decimal("1")
+ True
"""
return a.is_signed()
def is_snan(self, a):
- """Returns 1 if the operand is a signaling NaN, otherwise returns 0.
+ """Return True if the operand is a signaling NaN;
+ otherwise return False.
>>> ExtendedContext.is_snan(Decimal('2.50'))
- Decimal("0")
+ False
>>> ExtendedContext.is_snan(Decimal('NaN'))
- Decimal("0")
+ False
>>> ExtendedContext.is_snan(Decimal('sNaN'))
- Decimal("1")
+ True
"""
return a.is_snan()
def is_subnormal(self, a):
- """Returns 1 if the operand is subnormal, otherwise returns 0.
+ """Return True if the operand is subnormal; otherwise return False.
>>> c = ExtendedContext.copy()
>>> c.Emin = -999
>>> c.Emax = 999
>>> c.is_subnormal(Decimal('2.50'))
- Decimal("0")
+ False
>>> c.is_subnormal(Decimal('0.1E-999'))
- Decimal("1")
+ True
>>> c.is_subnormal(Decimal('0.00'))
- Decimal("0")
+ False
>>> c.is_subnormal(Decimal('-Inf'))
- Decimal("0")
+ False
>>> c.is_subnormal(Decimal('NaN'))
- Decimal("0")
+ False
"""
return a.is_subnormal(context=self)
def is_zero(self, a):
- """Returns 1 if the operand is a zero, otherwise returns 0.
+ """Return True if the operand is a zero; otherwise return False.
>>> ExtendedContext.is_zero(Decimal('0'))
- Decimal("1")
+ True
>>> ExtendedContext.is_zero(Decimal('2.50'))
- Decimal("0")
+ False
>>> ExtendedContext.is_zero(Decimal('-0E+2'))
- Decimal("1")
+ True
"""
return a.is_zero()