gh-119896: Fix repl ctrl-z on Windows #122217
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Is the design of the original REPL that required an Enter after a CTRL-Z actually desirable to repeat? I always found that clunky about the original REPL. IPython on Windows doesn't even implement ^Z handling. (Sure, it doesn't crash with missing SIGSTOP but it complains about an "invalid non-prinatble character U+001A"). ptpython on Windows ignores ^Z entirely. Even Windows' own terminal applications don't agree on the behavior of CTRL-Z. cmd.exe behaves like Python's old REPL, while PowerShell uses CTRL-Z for backspace. I would vote for ^Z to exit immediately, just as ^D does. |
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@zooba, what's your take? |
| @@ -52,7 +54,10 @@ def disp_str(buffer: str) -> tuple[str, list[int]]: | |||
| b: list[int] = [] | |||
| s: list[str] = [] | |||
| for c in buffer: | |||
| if ord(c) < 128: | |||
| if c == '\x1a': | |||
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Would it make sense to put '\x1a' in a constant like CTRL_Zso it's obvious what it represents?
I think it's even more inconsistent than that :) For what it's worth for me Ctrl-Z just adds the "^Z" character as an input in both cmd and powershell, and in cmd that seems to be ignored, while in powershell that seems to be inputted as a character similar to Python when it's not at the beginning of the line. But I'm also on Windows 10.
The main reason why I tried to preserve the behavior is that I'm a little bit loathe to mess with peoples muscle memory. If people do want a less clunky way they've actually still got it - Ctrl-D and it's consistent across operation systems! :) Maybe a lesser concern is if someone coming from Linux is on Windows and hits Ctrl-Z w/o thinking and it immediately exits. That's a lot less recoverable than it is on Linux/Mac. But we could just go with the patch @devdanzin offered in the issue if there's a strong desire to change the behavior. |
You convinced me. |
…onGH-122217) (cherry picked from commit d1a1bca) Co-authored-by: Dino Viehland <dinoviehland@meta.com>
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GH-122451 is a backport of this pull request to the 3.13 branch. |
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Please, please, please add refs (such as Working with this later is hard. Please. |
Fixes Ctrl-Z to behave like the existing Windows REPL:
Basically we get the ability to output the '\x1a' character as
^Z(knowing it has a length of 2) and we account for it's length in the output. To get the ability to quit we register a new command like "exit" or "quit". Finally we no longer register the keyboard shortcut on Windows.More of this could be wrapped up in sys.platform checks for win32, but I don't think they're strictly necessary - Ctrl-Z will just immediately do a suspend on Linux and will never be in the input.
We could extend this to more Ctrl-characters (e.g. you can type "Ctrl-E" and get
^Ein the input and there's many more that don't map to useful control keys) but I'm not sure it has any value. We could also drop making Ctrl-D exit the process on Windows but I suspect this is a general usability improvement for people working on both platforms.