PEP 240, Adding a Rational Literal to Python, Moshe Zadka

[checking in for Moshe, after editorial, spell check, and formatting
passes by Barry]

pep-0240.txt

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+PEP: 240
+Title: Adding a Rational Literal to Python
+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:
+
+
+Abstract
+
+    A different PEP[1] suggests adding a builtin rational type to
+    Python.  This PEP suggests changing the ddd.ddd float literal to a
+    rational in Python, and modifying non-integer division to return
+    it.
+
+
+Rationale
+
+    Rational numbers are useful, and are much harder to use without
+    literals.  Making the "obvious" non-integer type one with more
+    predictable semantics will surprise new programmers less then
+    using floating point numbers.
+
+
+Proposal
+
+    Literals conforming to the regular expression '\d*.\d*' will be
+    rational numbers.
+
+
+Backwards Compatibility
+
+    The only backwards compatible issue is the type of literals
+    mentioned above.  The following migration is suggested:
+
+    1. "from __future__ import rational_literals" will cause all such
+       literals to be treated as rational numbers.
+
+    2. Python 2.2 will have a warning, turned off by default, about
+       such literals in the absence of a __future__ statement.  The
+       warning message will contain information about the __future__
+       statement, and indicate that to get floating point literals,
+       they should be suffixed with "e0".
+
+    3. Python 2.3 will have the warning turned on by default.  This
+       warning will stay in place for 24 months, at which time the
+       literals will be rationals and the warning will be removed.
+
+
+References
+
+    [1] PEP 239, Adding a Rational Type to Python, Zadka,
+        http://python.sourceforge.net/peps/pep-0239.html
+
+
+Copyright
+
+    This document has been placed in the public domain.
+
+
+
+Local Variables:
+mode: indented-text
+indent-tabs-mode: nil
+End: