Lichen

Annotated lib/__builtins__/exception/program.py

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2017-03-23 Paul Boddie file changeset files shortlog Represent integers as __attr values with bit 0 set. Since pointers must be aligned (to four-byte boundaries on many modern systems, maybe two-byte boundaries on older or embedded systems, eight-byte boundaries on some 64-bit systems), any value with bit 0 set will not be referencing an object. This avoids allocating objects for integers and instead just allows them to be passed around. Bit 0 needs to be tested when attributes are accessed, and for integers, a common instance is employed to provide any instance attributes, an instance table reference and a reference to the integer class. integers-as-tagged-attrs
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#!/usr/bin/env python
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"""
 
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Program exception objects.
 
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Copyright (C) 2015, 2016, 2017 Paul Boddie <paul@boddie.org.uk>
 
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This program is free software; you can redistribute it and/or modify it under
 
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the terms of the GNU General Public License as published by the Free Software
 
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Foundation; either version 3 of the License, or (at your option) any later
 
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version.
 
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This program is distributed in the hope that it will be useful, but WITHOUT
 
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 
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FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 
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details.
 
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You should have received a copy of the GNU General Public License along with
 
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this program.  If not, see <http://www.gnu.org/licenses/>.
 
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"""
 
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class SyntaxError(Exception):
 
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    "A general syntax error."
 
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    pass
 
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class IndentationError(SyntaxError): pass
 
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class TabError(SyntaxError): pass
 
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# vim: tabstop=4 expandtab shiftwidth=4