[Python-Dev] getch() in msvcrt does not accept extended characters. (original) (raw)

Darryl Dixon esrever_otua at pythonhacker.is-a-geek.net
Fri Jul 1 06:29:34 CEST 2005

Hi,

I'm sorry, I don't seem to have done a very good job at explaining

the situation. I'll try again: 'getch()' is a low-level function provided on Windows to capture a single character of input from a user, /without echoing it to the screen/. As far as I can tell there's no other way of doing this with Python on Windows. The Python interface to this function is in the C code in msvcrtmodule.c, which has a (very thin) wrapper around the raw OS system call. Microsoft provide a way of accepting both normal ASCII codes, and extended characters via this system call. Currently, the Python wrapper in msvcrtmodule.c only supports the semantics of getting the bare ASCII codes, and not the extended characters. I would strongly suggest that it should support both.

So, I guess in answer to the questions raised below;

  1. I can't do it in Python code without getch() (hence the original email)

  2. I would argue that in fact getch() is 'broken' in its current Python implementation, as it doesn't support what the OS implies /should/ be supported (and, indeed, if I input an extended character in response to a 'getch()' call, all I get back currently is an empty string).

Finally, I've dug a little deeper, and it looks as though if (ch > UCHAR_MAX) then it would have to call PyUnicode_FromUnicode(s, 1) instead.

Is it worth sending in a patch to the sourceforge patch-tracker implementing this? Is it OK for msvcrt_getch to return Unicode when appropriate?

Thoughts?

Hope this helps, D

Fredrik wrote: >Darryl Dixon wrote: >>> Microsoft support capturing extended characters via getch, but it requires making a >> second call to getch() if one of the 'magic' returns is encountered in the first call (0x00 >> or 0xE0). >>so why not do that in your python code? >>> The relevant chunk of code in Python that would probably need to be >> changed to support this appears to be in msvcrtmodule.c: >>if you change msvcrt, you'll break all the programs that uses getch() in >the prescribed way... >>

Darryl Dixon <esrever_otua at pythonhacker.is-a-geek.net>

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