Issue #16469: Fraction(float('nan')) and Fraction(float('inf')) now raise ValueError and OverflowError (resp.), not TypeError.

1 files changed, 9 insertions, 5 deletions

diff --git a/Lib/fractions.py b/Lib/fractions.py
index 8be52d2..79e83ff 100644
--- a/Lib/fractions.py
+++ b/Lib/fractions.py
@@ -182,8 +182,10 @@ class Fraction(numbers.Rational):
         elif not isinstance(f, float):
             raise TypeError("%s.from_float() only takes floats, not %r (%s)" %
                             (cls.__name__, f, type(f).__name__))
-        if math.isnan(f) or math.isinf(f):
-            raise TypeError("Cannot convert %r to %s." % (f, cls.__name__))
+        if math.isnan(f):
+            raise ValueError("Cannot convert %r to %s." % (f, cls.__name__))
+        if math.isinf(f):
+            raise OverflowError("Cannot convert %r to %s." % (f, cls.__name__))
         return cls(*f.as_integer_ratio())
 
     @classmethod
@@ -196,9 +198,11 @@ class Fraction(numbers.Rational):
             raise TypeError(
                 "%s.from_decimal() only takes Decimals, not %r (%s)" %
                 (cls.__name__, dec, type(dec).__name__))
-        if not dec.is_finite():
-            # Catches infinities and nans.
-            raise TypeError("Cannot convert %s to %s." % (dec, cls.__name__))
+        if dec.is_infinite():
+            raise OverflowError(
+                "Cannot convert %s to %s." % (dec, cls.__name__))
+        if dec.is_nan():
+            raise ValueError("Cannot convert %s to %s." % (dec, cls.__name__))
         sign, digits, exp = dec.as_tuple()
         digits = int(''.join(map(str, digits)))
         if sign: