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Date: Mon, 1 Apr 2013 09:32:04 +1100
Subject: Re: Why does 1**2**3**4**5 raise a MemoryError?
From: Chris Angelico <rosuav@gmail.com>
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Xref: csiph.com comp.lang.python:42430

On Mon, Apr 1, 2013 at 9:28 AM, Chris Angelico <rosuav@gmail.com> wrote:
> On Mon, Apr 1, 2013 at 9:06 AM, Alex <foo@email.invalid> wrote:
>> Really?
>>
>> The Python 3 documentation
>> (http://docs.python.org/3/reference/expressions.html) says in section
>> 6.14 (Evaluation order) that "Python evaluates expressions from left to
>> right" (an exception being when evaluating assignments, in which case
>> the RHS of the assignment is calculated first, in left-to-right order).
>>
>> Section 6.4 discusses the power operator specifically and does not
>> contradict 6.14 except that the power operator uses right-to-left
>> evaluation in the presence of unparenthesized unary operators.
>
> http://docs.python.org/3/reference/expressions.html#operator-precedence
>
> Opening paragraph, "... exponentiation, which groups from right to
> left". It follows the obvious expectation from mathematics. (The OP is
> using Python 2, but the same applies.)

Though your point about 6.14 is still true. It states the order that
the integers will be evaluated in. Note one of the examples given:

expr1 + expr2 * (expr3 - expr4)

The evaluation of the expression starts with 3 and 4, then picks up 2,
then 1, but the operands themselves are evaluated left to right.

ChrisA