auto-increment operator - why no syntax error?

[Karthik Gurusamy]

I see python doesn't have ++ or -- operators unlike say, C.
I read some reasonings talking about immutable scalars and using ++/--
doesn't make much sense in python (not sure if ++i is that far-fetched
compared to the allowed i += 1)

In any case, I accidentally wrote ++n in python and it silently
accepted the expression and it took me a while to debug the problem.

Why are the following accepted even without a warning about syntax
error?
(I would expect the python grammar should catch these kind of syntax
errors)

>>n = 1
2 * +++++ n

2

>>n += 1
n

2

>>++n

2

Karthik

[Chris M]

On Dec 8, 7:58 pm, Karthik Gurusamy <[e-mail]:

I see python doesn't have ++ or -- operators unlike say, C.
I read some reasonings talking about immutable scalars and using ++/--
doesn't make much sense in python (not sure if ++i is that far-fetched
compared to the allowed i += 1)

In any case, I accidentally wrote ++n in python and it silently
accepted the expression and it took me a while to debug the problem.

Why are the following accepted even without a warning about syntax
error?
(I would expect the python grammar should catch these kind of syntax
errors)

>n = 1
2 * +++++ n

2

>n += 1
n

2

>++n

2

Karthik

There is a unary operator "+". When you write ++n, it's evaluating +n,
and then +(that result).

[Marc 'BlackJack' Rintsch]

On Sat, 08 Dec 2007 16:58:25 -0800, Karthik Gurusamy wrote:

Why are the following accepted even without a warning about syntax
error?
(I would expect the python grammar should catch these kind of syntax
errors)

>>>n = 1
2 * +++++ n

2

>>>n += 1
n

2

>>>++n

2

There is no syntax error. It is just some unary pluses "chained". Maybe
unexpected but no syntax error.

Ciao,
Marc 'BlackJack' Rintsch