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-rw-r--r--Misc/NEWS23
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@@ -57,6 +57,29 @@ Type/class unification and new-style classes
Core and builtins
+- There's a new warning category, FutureWarning. This is used to warn
+ about a number of situations where the value or sign of an integer
+ result will change in Python 2.4 as a result of PEP 237 (integer
+ unification). The warnings implement stage B0 mentioned in that
+ PEP. The warnings are about the following situations:
+
+ - Octal and hex literals without 'L' prefix in the inclusive range
+ [0x80000000..0xffffffff]; these are currently negative ints, but
+ in Python 2.4 they will be positive longs with the same bit
+ pattern.
+
+ - Left shifts on integer values that cause the outcome to lose
+ bits or have a different sign than the left operand. To be
+ precise: x<<n where this currently doesn't yield the same value
+ as long(x)<<n; in Python 2.4, the outcome will be long(x)<<n.
+
+ - Conversions from ints to string that show negative values as
+ unsigned ints in the inclusive range [0x80000000..0xffffffff];
+ this affects the functions hex() and oct(), and the string
+ formatting codes %u, %o, %x, and %X. In Python 2.4, these will
+ show signed values (e.g. hex(-1) currently returns "0xffffffff";
+ in Python 2.4 it will return "-0x1").
+
- When multiplying very large integers, a version of the so-called
Karatsuba algorithm is now used. This is most effective if the
inputs have roughly the same size. If they both have about N digits,