On 11/07/2015 17:56, Ian Kelly wrote:
On Sat, Jul 11, 2015 at 10:02 AM, Stefan Ram <r...@zedat.fu-berlin.de> wrote:
I look at Python 3.4.3:
a_expr ::= m_expr | a_expr "+" m_expr | a_expr "-" m_expr
So, »not 0« must be an »m_expr« when used as the right operand of »+«.
m_expr ::= u_expr | m_expr "*" u_expr | m_expr "//" u_expr | m_expr "/" u_expr | m_expr
"%" u_expr
u_expr ::= power | "-" u_expr | "+" u_expr | "~" u_expr
power ::= primary ["**" u_expr]
primary ::= atom | attributeref | subscription | slicing | call
atom ::= identifier | literal | enclosure
enclosure ::= parenth_form | list_display | dict_display | set_display |
generator_expression | yield_atom
How can there be a »not«?
»not« is used in
not_test ::= comparison | "not" not_test
and_test ::= not_test | and_test "and" not_test
or_test ::= and_test | or_test "or" and_test
conditional_expression ::= or_test ["if" or_test "else" expression]
expression_nocond ::= or_test | lambda_expr_nocond
expression ::= conditional_expression | lambda_expr
, but an »expression« is not an »m_expr«.
I must concur. The grammar as written does not actually produce 1 +
not 0. I think it's still worthwhile opening a bug, because the
behavior is surprising and possibly not intentional.
http://bugs.python.org/issue24612
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