[Python-checkins] r68188 - in python/branches/release26-maint: Lib/fractions.py Lib/test/test_fractions.py Misc/NEWS

[raymond.hettinger]

Author: raymond.hettinger
Date: Sat Jan  3 10:24:18 2009
New Revision: 68188

Log:
Fractions.from_float() no longer loses precision with large integer inputs.

Modified:
   python/branches/release26-maint/Lib/fractions.py
   python/branches/release26-maint/Lib/test/test_fractions.py
   python/branches/release26-maint/Misc/NEWS

Modified: python/branches/release26-maint/Lib/fractions.py
==============================================================================
--- python/branches/release26-maint/Lib/fractions.py	(original)
+++ python/branches/release26-maint/Lib/fractions.py	Sat Jan  3 10:24:18 2009
@@ -111,7 +111,7 @@
 
         """
         if isinstance(f, numbers.Integral):
-            f = float(f)
+            return cls(f)
         elif not isinstance(f, float):
             raise TypeError("%s.from_float() only takes floats, not %r (%s)" %
                             (cls.__name__, f, type(f).__name__))

Modified: python/branches/release26-maint/Lib/test/test_fractions.py
==============================================================================
--- python/branches/release26-maint/Lib/test/test_fractions.py	(original)
+++ python/branches/release26-maint/Lib/test/test_fractions.py	Sat Jan  3 10:24:18 2009
@@ -139,6 +139,8 @@
     def testFromFloat(self):
         self.assertRaises(TypeError, F.from_float, 3+4j)
         self.assertEquals((10, 1), _components(F.from_float(10)))
+        bigint = 1234567890123456789
+        self.assertEquals((bigint, 1), _components(F.from_float(bigint)))
         self.assertEquals((0, 1), _components(F.from_float(-0.0)))
         self.assertEquals((10, 1), _components(F.from_float(10.0)))
         self.assertEquals((-5, 2), _components(F.from_float(-2.5)))

Modified: python/branches/release26-maint/Misc/NEWS
==============================================================================
--- python/branches/release26-maint/Misc/NEWS	(original)
+++ python/branches/release26-maint/Misc/NEWS	Sat Jan  3 10:24:18 2009
@@ -56,6 +56,9 @@
 Library
 -------
 
+- Fractions.from_float() no longer loses precision for integers to big to
+  cast as floats.
+
 - Issue 4790: The nsmallest() and nlargest() functions in the heapq module
   did unnecessary work in the common case where no key function was specified.