Merged revisions 60245-60277 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/trunk
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r60246 | guido.van.rossum | 2008-01-24 18:58:05 +0100 (Thu, 24 Jan 2008) | 2 lines
Fix test67.py from issue #1303614.
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r60248 | raymond.hettinger | 2008-01-24 19:05:54 +0100 (Thu, 24 Jan 2008) | 1 line
Clean-up and speed-up code by accessing numerator/denominator directly. There's no reason to enforce readonliness
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r60249 | raymond.hettinger | 2008-01-24 19:12:23 +0100 (Thu, 24 Jan 2008) | 1 line
Revert 60189 and restore performance.
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r60250 | guido.van.rossum | 2008-01-24 19:21:02 +0100 (Thu, 24 Jan 2008) | 5 lines
News about recently fixed crashers:
- A few crashers fixed: weakref_in_del.py (issue #1377858);
loosing_dict_ref.py (issue #1303614, test67.py);
borrowed_ref_[34].py (not in tracker).
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r60252 | thomas.heller | 2008-01-24 19:36:27 +0100 (Thu, 24 Jan 2008) | 7 lines
Use a PyDictObject again for the array type cache; retrieving items
from the WeakValueDictionary was slower by nearly a factor of 3.
To avoid leaks, weakref proxies for the array types are put into the
cache dict, with weakref callbacks that removes the entries when the
type goes away.
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r60253 | thomas.heller | 2008-01-24 19:54:12 +0100 (Thu, 24 Jan 2008) | 2 lines
Replace Py_BuildValue with PyTuple_Pack because it is faster.
Also add a missing DECREF.
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r60254 | raymond.hettinger | 2008-01-24 20:05:29 +0100 (Thu, 24 Jan 2008) | 1 line
Add support for trunc().
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r60255 | thomas.heller | 2008-01-24 20:15:02 +0100 (Thu, 24 Jan 2008) | 5 lines
Invert the checks in get_[u]long and get_[u]longlong. The intent was
to not accept float types; the result was that integer-like objects
were not accepted.
Ported from release25-maint.
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r60256 | raymond.hettinger | 2008-01-24 20:30:19 +0100 (Thu, 24 Jan 2008) | 1 line
Add support for int(r) just like the other numeric classes.
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r60263 | raymond.hettinger | 2008-01-24 22:23:58 +0100 (Thu, 24 Jan 2008) | 1 line
Expand tests to include nested graph structures.
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r60264 | raymond.hettinger | 2008-01-24 22:47:56 +0100 (Thu, 24 Jan 2008) | 1 line
Shorter pprint's for empty sets and frozensets. Fix indentation of frozensets. Add tests including two complex data structures.
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r60265 | amaury.forgeotdarc | 2008-01-24 23:51:18 +0100 (Thu, 24 Jan 2008) | 14 lines
#1920: when considering a block starting by "while 0", the compiler optimized the
whole construct away, even when an 'else' clause is present::
while 0:
print("no")
else:
print("yes")
did not generate any code at all.
Now the compiler emits the 'else' block, like it already does for 'if' statements.
Will backport.
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r60266 | amaury.forgeotdarc | 2008-01-24 23:59:25 +0100 (Thu, 24 Jan 2008) | 2 lines
News entry for r60265 (Issue 1920).
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r60269 | raymond.hettinger | 2008-01-25 00:50:26 +0100 (Fri, 25 Jan 2008) | 1 line
More code cleanup. Remove unnecessary indirection to useless class methods.
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r60270 | raymond.hettinger | 2008-01-25 01:21:54 +0100 (Fri, 25 Jan 2008) | 1 line
Add support for copy, deepcopy, and pickle.
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r60271 | raymond.hettinger | 2008-01-25 01:33:45 +0100 (Fri, 25 Jan 2008) | 1 line
Mark todos and review comments.
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r60272 | raymond.hettinger | 2008-01-25 02:13:12 +0100 (Fri, 25 Jan 2008) | 1 line
Add one other review comment.
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r60273 | raymond.hettinger | 2008-01-25 02:23:38 +0100 (Fri, 25 Jan 2008) | 1 line
Fix-up signature for approximation.
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r60274 | raymond.hettinger | 2008-01-25 02:46:33 +0100 (Fri, 25 Jan 2008) | 1 line
More design notes
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r60276 | neal.norwitz | 2008-01-25 07:37:23 +0100 (Fri, 25 Jan 2008) | 6 lines
Make the test more robust by trying to reconnect up to 3 times
in case there were transient failures. This will hopefully silence
the buildbots for this test. As we find other tests that have a problem,
we can fix with a similar strategy assuming it is successful. It worked
on my box in a loop for 10+ runs where it would have an exception otherwise.
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r60277 | neal.norwitz | 2008-01-25 09:04:16 +0100 (Fri, 25 Jan 2008) | 4 lines
Add prototypes to get the mathmodule.c to compile on OSF1 5.1 (Tru64)
and eliminate a compiler warning in floatobject.c. There might be
a better way to go about this, but it should be good enough for now.
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diff --git a/Lib/rational.py b/Lib/rational.py
index 4a56cf2..89b622c 100755
--- a/Lib/rational.py
+++ b/Lib/rational.py
@@ -13,7 +13,7 @@
RationalAbc = numbers.Rational
-def _gcd(a, b):
+def _gcd(a, b): # XXX This is a useful function. Consider making it public.
"""Calculate the Greatest Common Divisor.
Unless b==0, the result will have the same sign as b (so that when
@@ -39,6 +39,8 @@
>>> _binary_float_to_ratio(-.25)
(-1, 4)
"""
+ # XXX Consider moving this to to floatobject.c
+ # with a name like float.as_intger_ratio()
if x == 0:
return 0, 1
@@ -79,6 +81,10 @@
_RATIONAL_FORMAT = re.compile(
r'^\s*(?P<sign>[-+]?)(?P<num>\d+)(?:/(?P<denom>\d+))?\s*$')
+# XXX Consider accepting decimal strings as input since they are exact.
+# Rational("2.01") --> s="2.01" ; Rational.from_decimal(Decimal(s)) --> Rational(201, 100)"
+# If you want to avoid going through the decimal module, just parse the string directly:
+# s.partition('.') --> ('2', '.', '01') --> Rational(int('2'+'01'), 10**len('01')) --> Rational(201, 100)
class Rational(RationalAbc):
"""This class implements rational numbers.
@@ -93,7 +99,7 @@
"""
- __slots__ = ('_numerator', '_denominator')
+ __slots__ = ('numerator', 'denominator')
# We're immutable, so use __new__ not __init__
def __new__(cls, numerator=0, denominator=1):
@@ -133,8 +139,8 @@
raise ZeroDivisionError('Rational(%s, 0)' % numerator)
g = _gcd(numerator, denominator)
- self._numerator = int(numerator // g)
- self._denominator = int(denominator // g)
+ self.numerator = int(numerator // g)
+ self.denominator = int(denominator // g)
return self
@classmethod
@@ -192,29 +198,22 @@
n, d = d, n
return cf
- @classmethod
- def approximate_from_float(cls, f, max_denominator):
- 'Best rational approximation to f with a denominator <= max_denominator'
+ def approximate(self, max_denominator):
+ 'Best rational approximation with a denominator <= max_denominator'
# XXX First cut at algorithm
# Still needs rounding rules as specified at
# http://en.wikipedia.org/wiki/Continued_fraction
- cf = cls.from_float(f).as_continued_fraction()
+ if self.denominator <= max_denominator:
+ return self
+ cf = self.as_continued_fraction()
result = Rational(0)
for i in range(1, len(cf)):
- new = cls.from_continued_fraction(cf[:i])
+ new = self.from_continued_fraction(cf[:i])
if new.denominator > max_denominator:
break
result = new
return result
- @property
- def numerator(a):
- return a._numerator
-
- @property
- def denominator(a):
- return a._denominator
-
def __repr__(self):
"""repr(self)"""
return ('Rational(%r,%r)' % (self.numerator, self.denominator))
@@ -226,6 +225,16 @@
else:
return '%s/%s' % (self.numerator, self.denominator)
+ """ XXX This section needs a lot more commentary
+
+ * Explain the typical sequence of checks, calls, and fallbacks.
+ * Explain the subtle reasons why this logic was needed.
+ * It is not clear how common cases are handled (for example, how
+ does the ratio of two huge integers get converted to a float
+ without overflowing the long-->float conversion.
+
+ """
+
def _operator_fallbacks(monomorphic_operator, fallback_operator):
"""Generates forward and reverse operators given a purely-rational
operator and a function from the operator module.
@@ -299,18 +308,15 @@
"""a // b"""
return math.floor(a / b)
- @classmethod
- def _mod(cls, a, b):
+ def __mod__(a, b):
+ """a % b"""
div = a // b
return a - b * div
- def __mod__(a, b):
- """a % b"""
- return a._mod(a, b)
-
def __rmod__(b, a):
"""a % b"""
- return b._mod(a, b)
+ div = a // b
+ return a - b * div
def __pow__(a, b):
"""a ** b
@@ -369,6 +375,8 @@
else:
return a.numerator // a.denominator
+ __int__ = __trunc__
+
def __floor__(a):
"""Will be math.floor(a) in 3.0."""
return a.numerator // a.denominator
@@ -410,6 +418,7 @@
float must have the same hash as that float.
"""
+ # XXX since this method is expensive, consider caching the result
if self.denominator == 1:
# Get integers right.
return hash(self.numerator)
@@ -481,3 +490,18 @@
def __bool__(a):
"""a != 0"""
return a.numerator != 0
+
+ # support for pickling, copy, and deepcopy
+
+ def __reduce__(self):
+ return (self.__class__, (str(self),))
+
+ def __copy__(self):
+ if type(self) == Rational:
+ return self # I'm immutable; therefore I am my own clone
+ return self.__class__(self.numerator, self.denominator)
+
+ def __deepcopy__(self, memo):
+ if type(self) == Rational:
+ return self # My components are also immutable
+ return self.__class__(self.numerator, self.denominator)