argparse does not work with Cython on Windows

Question

I am writing a Windows app. using Python/Cython and compiling using MingW GNU C compiler and an MSYS2 terminal.

The small snippet code below shows the issue:

import argparse

if __name__ == "__main__":

    parser = argparse.ArgumentParser(description='Argparse Cython Test')
    parser.add_argument(
        '--run',
        type=str,
        default='',
        dest="runFile",
        required=False,
        help='Execute this file.')

    args = parser.parse_args()
    print ("args -- ", args)

#endif main

I translate the code into C with:

> cython -3 --embed -o argTest.c argTest.py

(Side note: For some reason the emitted C code generates a main function int wmain () instead of int main() so I do that change using a sed script). And then compile with MingW GCC:

> gcc -v -O3 -I/d/Python3/include/ -L /d/Python3/libs/ -o argTest argTest.c -lpython36 -lm -ldl -Wl,--subsystem,windows

I see this output when I run the executable with the argparse options -- seems to be some unicode characters:

> ./argTest.exe -h                                         
usage: \u3a44\u4d5c\u2079\u7453\u6675\u5c66\u6556\u4378\u646d\u7950\u615c\u6772\u6554\u7473\u652e\u6578\u5200\u433d\u5c3a\u4957\ua4f3\u4bf8\u3ff4\u0d00\u682d\u0200▒\u02b1\ua4f3\u4bf8\u3ff0\u0e00.\u02b1▒\u02b1\ua4b4\u0cf8\u3ff0\u0800 [-h] [--run RUNFILE]
\u3a44\u4d5c\u2079\u7453\u6675\u5c66\u6556\u4378\u646d\u7950\u615c\u6772\u6554\u7473\u652e\u6578\u5200\u433d\u5c3a\u4957\ua4f3\u4bf8\u3ff4\u0d00\u682d\u0200▒\u02b1\ua4f3\u4bf8\u3ff0\u0e00.\u02b1▒\u02b1\ua4b4\u0cf8\u3ff0\u0800: error: unrecognized arguments: \u682d\u0200▒\u02b1\ua4f3\u4bf8\u3ff0\u0e00.\u02b1▒\u02b1\ua4b4\u0cf8\u3ff0\u0800

Without the argparse options, the executable runs fine. My application (using wxPython) runs fine on Windows without using argparse options.

Anyone knows what may be happening here?

Thanks

do you change only the name `wmain`-> `main` or also the type of parameter argv from `wchar_t**`->`char**`? — ead, Aug 20 '18 at 04:43
I have changed `int wmain(int argc, wchar_t **argv) ` to `int main(int argc, wchar_t **argv)` in the `#elif defined(WIN32) || defined(MS_WINDOWS)` clause — user0, Aug 20 '18 at 07:36
I don't know Windows well enough, but probably you have also to change wchar_t to char, otherwise you are probably reinterpreting ascii as unicode. — ead, Aug 20 '18 at 07:45
Thanks for the tip. I tried that -- now it doesn't print anything at all. I see warnings because Python3 libs expect wchar_t parameters. — user0, Aug 20 '18 at 14:49

score 0 · Answer 1 · answered Aug 29 '18 at 13:53

0

argparse is working fine, but your mixing Python 3 UTF-8 string and char*. Changing wmain for main means you will be handling you inputs as ASCII. Check answers here about how to enable wmain in MINGW compilers.

answered Aug 29 '18 at 13:53

yorodm

4,359
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Thanks for the link. argparse is working fine after switching to the 64-bit MinGW and compiling with -municode (with target i686-w64-mingw32). No mode to Cython output is required. – user0 Aug 30 '18 at 03:33

argparse does not work with Cython on Windows

1 Answers1