On Fri, 16 Oct 2020, 23:04 Stefano Borini, <stefano.bor...@gmail.com> wrote:
> Hello, > > I am trying to implement PEP-637, and I started modifying the parser > and the grammar, but I don't know what I am missing. > > The PR is here > > > https://github.com/python/cpython/compare/master...stefanoborini:PEP-637-implementation-attempt-1?expand=1 > > It includes other stuff but the core is that I extended the Subscript > in the asdl to accept the keyword args > > | Subscript(expr value, expr slice, keyword* keywords, expr_context ctx) > > which seems to work: > > >>> ast.parse('a[3]').body[0].value.keywords > [] > > I also added a few "productions" (I believe they are called like this, > my compiler theory is very approximated), one of which is now > > primary[expr_ty]: > .... > | a=primary '[' b=slices c=[',' k=kwargs {k}]']' { > _Py_Subscript(a, b, c, Load, EXTRA) } > > I also tried with additional formats like > > | a=primary '[' b=slices c=kwargs ']' { _Py_Subscript(a, b, c, > Load, EXTRA) } > > or even just > > | a=primary '[' c=kwargs ']' { _Py_Subscript(a, NULL, c, Load, EXTRA) } > > but I always get a SyntaxError: > > >>> ast.parse('a[k=3]').body[0].value.keywords > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > File "/Users/sbo/Work/Projects/stefanoborini/cpython/Lib/ast.py", > line 50, in parse > return compile(source, filename, mode, flags, > File "<unknown>", line 1 > a[k=3] > ^ > SyntaxError: invalid syntax > > Note that I always recreated ast parser and pegen.c with 'make > regen-all' and recompiled with make. > I tried to enable debug and print the pegen.c debug, but it's a bit > heavy and I could not immediately spot the issue. I suspect I am > missing something somewhere. > Have you manually checked that the generated source in pegen.c contains your changes? You should be able to see by just looking for calls to _Py_Subscript, or other code snippets from the modified grammar. Or, you can introduce an error in the grammar's code snippets and check that you get the expected error. FWIW, I found I had to explicitly regenerate pegen.c with 'make regen-pegen'; 'make regen-all' wasn't enough. > Thanks > > > -- > Kind regards, > > Stefano Borini > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/RZYDHYZPTPGLBX4VCR6HTYGJ3GL2CWIX/ > Code of Conduct: http://python.org/psf/codeofconduct/ >
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