== '
I am coding python in emacs. However, somehow the python interpreter running in emacs manages to surprise me.
If I write
print()
print(__name__)
print(__name__=='__main__')
if __name__ == '__main__':
print("indeed")
in an emacs buffer, and tell emacs to start an interpreter and run the content of this buffer, I get a buffer containing
Python 3.3.5 (default, Mar 18 2014, 02:00:02)
[GCC 4.2.1 20070831 patched [FreeBSD]] on freebsd9
Type "help", "copyright", "credits" or "license" for more information.
>>>
__main__
True
>>>
(Both __main__ and True are the outputs from the print statement; the python buffer always displays the >>> and prints immediately after it. I am aware of this, this is not a problem.)
From the command line, both python and python -i show the 'indeed', as expected.
How is Emacs able to the inconsistency of evaluating __name__=='__main__' to True , while not executing things inside if __name__ == '__main__': ? And how do reconfigure it so it does not do so any more?
As @Wooble mentioned in the comment, it might be python.el issue: Cc Cc runs
python-shell-send-buffer function:
python-shell-send-buffer is an interactive compiled Lisp function in `python.el'.
(python-shell-send-buffer &optional ARG)
Send the entire buffer to inferior Python process. With prefix ARG allow execution of code inside blocks delimited by "if __name__=='__main__':"
ie, to print "indeed", add prefix Cu Cc Cc .
Q: I have tried to dig through python.el, and I am still not sure how and where it does this. Can you explain, so I can modify the default behaviour?
To find out what Cc Cc does in your case open a python file and type Mx describe-key RET followed by Cc Cc (actually press the keys). By default it runs python-shell-send-buffer function in python.el . You could redefine the keys to call the function with an argument so that Cc Cc would behave like Cu Cc Cc that enables running "if __name__=='__main__':" part:
;; Make C-c C-c behave like C-u C-c C-c in Python mode
(require 'python)
(define-key python-mode-map (kbd "C-c C-c")
(lambda () (interactive) (python-shell-send-buffer t)))
Once you have started the python shell, you can simply override the variable:
__name__ = 'repl'
This prevents any if __name__=='__main__': blocks from running on any subsequent Cc Cc invocations.
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