On 8/11/2012 7:13 PM, Chris Angelico wrote:
On Sun, Aug 12, 2012 at 8:30 AM, John Ladasky
<john_lada...@sbcglobal.net> wrote:
In [7]: 1 + not(len(L) % 2)
------------------------------------------------------------
File "<ipython console>", line 1
1 + not(len(L) % 2)
^
SyntaxError: invalid syntax
This appears to be a limitation of the parser; it's trying to
interpret "not" as a binary operator.
I think not. It is lower precedence than all arithmetic operators. The
following is worth knowing about and occasionally reviewing.
http://docs.python.org/py3k/reference/expressions.html#summary
() around % is not needed; not len(L) % 2 works same. So parser sees
1 + not len(L) % 2
with + given higher precedence than not, So it parses as (1 + not) and
croaks, as indicated by caret. (We humans see that that is impossible
and may boost the precedence in context.)
1 + (not(len(L) % 2))
== 1 + (not len(L) % 2)
Works just fine with parentheses to enforce the correct interpretation.
This also works in Python 3.2, fwiw (except that you need
list(range(5)) to create the sample list).
--
Terry Jan Reedy
--
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