GNU bug report logs - #39070
python interpreter within Emacs fails on simple test (syntax error)

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Package: emacs;

Reported by: Pierre ALBARÈDE <pa.com <at> free.fr>

Date: Fri, 10 Jan 2020 15:34:01 UTC

Severity: normal

Tags: notabug

Done: Lars Ingebrigtsen <larsi <at> gnus.org>

Bug is archived. No further changes may be made.

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Report forwarded to bug-gnu-emacs <at> gnu.org:
bug#39070; Package emacs. (Fri, 10 Jan 2020 15:34:02 GMT) Full text and rfc822 format available.

Acknowledgement sent to Pierre ALBARÈDE <pa.com <at> free.fr>:
New bug report received and forwarded. Copy sent to bug-gnu-emacs <at> gnu.org. (Fri, 10 Jan 2020 15:34:02 GMT) Full text and rfc822 format available.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Pierre ALBARÈDE <pa.com <at> free.fr>
To: bug-gnu-emacs <at> gnu.org
Subject: python interpreter within Emacs fails on simple test (syntax error)
Date: Fri, 10 Jan 2020 11:29:58 +0000
[Message part 1 (text/plain, inline)]
This small program

mac2011% cat bug.py
print(__name__ == "__main__")
#if True:
if __name__ == "__main__":
    print("main")
else:
    print("not main")

works well in Terminal :

mac2011% python bug.py
True
main

mac2011% python --version
Python 3.6.9 :: Anaconda, Inc.

but it does not work in Emacs python mode :

mac2011% Emacs -Q bug.py

(version)
"GNU Emacs 28.0.50 (build 1, x86_64-apple-darwin15.6.0, NS appkit-1404.47 
Version 10.11.6 (Build 15G22010))
 of 2020-01-09"

Files opens in (Python ElDoc) mode

Python menu

Start interpreter (C-c C-p)

Eval buffer (C-c C-c)

Python 3.6.9 |Anaconda, Inc.| (default,     Jul 30 2019, 13:42:17)
[GCC 4.2.1 Compatible Clang 4.0.1 (tags/RELEASE_401/final)] on darwin
Type "help", "copyright", "credits" or     "license" for more information.
>>> python.el: native completion setup loaded
>>> Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/alba/Documents/projets/plot time series/bug.py", line 5
    else:
       ^
SyntaxError: invalid syntax
>>>

Replacing 'if __name__ == "__main__":' by 'if True:', there is no more error.

Replacing "__main__" by "__main_", there is no more error.

Same with Python 3.7.6.

'print("main") if __name__ == '__main__' else  print("not main")' works.

Best regards.

-- 
Pierre ALBARÈDE



[smime.p7s (application/pkcs7-signature, attachment)]

Information forwarded to bug-gnu-emacs <at> gnu.org:
bug#39070; Package emacs. (Tue, 04 Feb 2020 00:04:02 GMT) Full text and rfc822 format available.

Message #8 received at 39070 <at> debbugs.gnu.org (full text, mbox):

From: Federico Tedin <federicotedin <at> gmail.com>
To: Pierre ALBARÈDE <pa.com <at> free.fr>
Cc: 39070 <at> debbugs.gnu.org
Subject: Re: bug#39070: python interpreter within Emacs fails on simple test
 (syntax error)
Date: Tue, 04 Feb 2020 01:03:49 +0100
> Replacing 'if __name__ == "__main__":' by 'if True:', there is no more error.
>
> Replacing "__main__" by "__main_", there is no more error.
>
> Same with Python 3.7.6.
>
> 'print("main") if __name__ == '__main__' else  print("not main")' works.
>
> Best regards.

Hello Pierre,

This behavior is due to `python-shell-send-buffer's SEND-MAIN
argument:

"When optional argument SEND-MAIN is non-nil, allow execution of
code inside blocks delimited by "if __name__== '__main__'" "

So when this argument is nil (the default), the whole block under "if
__name__== '__main__'" " will be removed (along the line containing the
"if" itself).
Your example breaks because you added an "else:" to your "if", so when
Emacs removes that part, a syntax error is raised.

Try the following test file:

print("1")

if __name__ == "__main__":
    print("2")

print("3")

Using C-c C-c on it should yield "1 3", but using C-u C-c C-c
(i.e. SEND-MAIN set to t) should yield "1 2 3".

Hope that helps.
- Fede




Information forwarded to bug-gnu-emacs <at> gnu.org:
bug#39070; Package emacs. (Sat, 30 Jan 2021 06:54:02 GMT) Full text and rfc822 format available.

Message #11 received at 39070 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Federico Tedin <federicotedin <at> gmail.com>
Cc: Pierre ALBARÈDE <pa.com <at> free.fr>, 39070 <at> debbugs.gnu.org
Subject: Re: bug#39070: python interpreter within Emacs fails on simple test
 (syntax error)
Date: Sat, 30 Jan 2021 07:53:20 +0100
Federico Tedin <federicotedin <at> gmail.com> writes:

> Using C-c C-c on it should yield "1 3", but using C-u C-c C-c
> (i.e. SEND-MAIN set to t) should yield "1 2 3".

So I guess this works as designed, and I'm closing this bug report.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no




Added tag(s) notabug. Request was from Lars Ingebrigtsen <larsi <at> gnus.org> to control <at> debbugs.gnu.org. (Sat, 30 Jan 2021 06:54:02 GMT) Full text and rfc822 format available.

bug closed, send any further explanations to 39070 <at> debbugs.gnu.org and Pierre ALBARÈDE <pa.com <at> free.fr> Request was from Lars Ingebrigtsen <larsi <at> gnus.org> to control <at> debbugs.gnu.org. (Sat, 30 Jan 2021 06:54:02 GMT) Full text and rfc822 format available.

bug archived. Request was from Debbugs Internal Request <help-debbugs <at> gnu.org> to internal_control <at> debbugs.gnu.org. (Sat, 27 Feb 2021 12:24:07 GMT) Full text and rfc822 format available.

This bug report was last modified 3 years and 30 days ago.

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