2003-01-29 10:07:17 -05:00
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PEP: 306
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Title: How to Change Python's Grammar
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Version: $Revision$
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Last-Modified: $Date$
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Author: Michael Hudson <mwh@python.net>
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2003-02-10 09:54:10 -05:00
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Status: Active
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2003-01-29 10:07:17 -05:00
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Type: Informational
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Content-Type: text/plain
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Created: 29-Jan-2003
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2003-01-30 10:22:56 -05:00
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Post-History: 30-Jan-2003
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2003-01-29 10:07:17 -05:00
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Abstract
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There's more to changing Python's grammar than editing
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Grammar/Grammar and Python/compile.c. This PEP aims to be a
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checklist of places that must also be fixed.
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It is probably incomplete. If you see omissions, just add them if
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you can -- you are not going to offend the author's sense of
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ownership. Otherwise submit a bug or patch and assign it to mwh.
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This PEP is not intended to be an instruction manual on Python
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2003-01-30 05:27:45 -05:00
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grammar hacking, for several reasons.
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2003-01-29 10:07:17 -05:00
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Rationale
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People are getting this wrong all the time; it took well over a
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year before someone noticed[1] that adding the floor division
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operator (//) broke the parser module.
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Checklist
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__ Grammar/Grammar: OK, you'd probably worked this one out :)
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__ Python/compile.c: you'll most likely need to edit both the
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actual compiler and the symtable builder (which is to say both
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the com_foo and the sym_foo functions).
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__ You may need to regenerate Lib/symbol.py and/or Lib/token.py.
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__ The parser module. Add some of your new syntax to test_parser,
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bang on parsermodule.c until it passes.
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__ The compiler package. A good test is to compile the standard
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library and test suite with the compiler package and then check
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it runs. You did add some of your new syntax to the test
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suite, didn't you? There's a script in Tools/compiler that
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does this.
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2003-01-30 05:27:45 -05:00
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__ If you've gone so far as to change the token structure of
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Python, then the tokenizer library module will need to be
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changed.
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__ Certain changes may require tweaks to the library module
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pycblr.
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__ Jython too will need work, but I don't know what. Explanations
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gratefully received.
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2003-01-29 10:07:17 -05:00
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References
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[1] SF Bug #676521, parser module validation failure
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http://www.python.org/sf/676521
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Copyright
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This document has been placed in the public domain.
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Local Variables:
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mode: indented-text
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indent-tabs-mode: nil
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sentence-end-double-space: t
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fill-column: 70
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End:
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