PEP: 237 Title: Unifying Long Integers and Integers Version: $Revision$ Author: pep@zadka.site.co.il (Moshe Zadka) Status: Draft Type: Standards Track Created: 11-Mar-2001 Python-Version: 2.2 Post-History: 16-Mar-2001 Abstract Python has both integers (machine word size integral) types, and long integers (unbounded integral) types. When integers operations overflow the machine registers, they raise an error. This PEP proposes to do away with the distinction, and unify the types from the perspective of both the Python interpreter and the C API. Rationale Having the machine word size exposed to the language hinders portability. For examples Python source files and .pyc's are not portable because of this. Many programs find a need to deal with larger numbers after the fact, and changing the algorithms later is not only bothersome, but hinders performance in the normal case. Literals A trailing 'L' at the end of an integer literal will stop having any meaning, and will be eventually phased out. This will be done using warnings when encountering such literals. The warning will be off by default in Python 2.2, on for 12 months, which will probably mean Python 2.3 and 2.4, and then will no longer be supported. Builtin Functions The function long() will call the function int(), issuing a warning. The warning will be off in 2.2, and on for two revisions before removing the function. A FAQ will be added to explain that a solutions for old modules are: long=int at the top of the module, or: import __builtin__ __builtin__.long=int In site.py. C API All PyLong_As* will call PyInt_As*. If PyInt_As* does not exist, it will be added. Similarly for PyLong_From*. A similar path of warnings as for the Python builtins will be followed. Overflows When an arithmetic operation on two numbers whose internal representation is as machine-level integers returns something whose internal representation is a bignum, a warning which is turned off by default will be issued. This is only a debugging aid, and has no guaranteed semantics. Implementation The PyInt type's slot for a C long will be turned into a union { long i; struct { unsigned long length; digit digits[1]; } bignum; }; Only the n-1 lower bits of the long have any meaning; the top bit is always set. This distinguishes the union. All PyInt functions will check this bit before deciding which types of operations to use. Jython Issues Jython will have a PyInt interface which is implemented by both from PyFixNum and PyBigNum. Open Issues What to do about sys.maxint? What to do about PyInt_AS_LONG failures? What do do about %u, %o, %x formatting operators? How to warn about << not cutting integers? Should the overflow warning be on a portable maximum size? Will unification of types and classes help with a more straightforward implementations? Define an C API that can be used to find out what the representation of an int is. Copyright This document has been placed in the public domain. Local Variables: mode: indented-text indent-tabs-mode: nil End: