On Fri, Sep 29, 2017 at 05:53:58AM +0000, Wren Turkal wrote:
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The basic idea is to add fin, fout, and ferr file object parameters and default to using what is used today when the args are not specified. I believe this would be useful to allow captures input and send output to specific files when using input. The input builtin has some logic to use readline if it's available. It would be nice to be able to use this same logic no matter what files are being used for input/output.
I've done the whole "set stdout and stdin, call input, reset stdout and stdin" dance, and so I like this concept of being able to easily use input() non-interactively. I think your basic idea is a good one.
I wonder what you think the ferr parameter will do? As far as I know, input() doesn't use stderr.
I also don't think much of your parameter names. They strike me as very C-like, rather than Pythonic.
So my proposal is:
input(prompt, *, infile, outfile)
where infile must be a file-like object with a read() method, suitable for replacing stdin, and outfile must be a file-like object with a write() method suitable for replacing stdout.
This is meant to turn code like the following:
orig_stdin = sys.stdin orig_stdout = sys.stdout with open('/dev/tty', 'r+') as f: sys.stdin = f sys.stdout = f name = input('Name? ')
sys.stdin = orig_stdin sys.stdout = orig_stdout print(name)
For production use, that should be wrapped in a try...finally:
try: ... finally: sys.stdin = orig_stdin sys.stdout = orig_stdout
into something more like this:
with open('/dev/tty', 'r+') as f: name = input('Name? ', fin=f, fout=f)
print(name)
I like it very much.
But as an alternative, perhaps all we really need is a context manager to set the std* files:
with open('/dev/tty', 'r+') as f: with stdio(stdin=f, stdout=f): name = input('Name? ')
print(name)
That's nearly as nice, and is possibly useful in more situations. Or maybe we should have both?
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Would love to see if anyone else is interested in this. I think it's pretty cool that the core logic really didn't need to be changed other than plumbing in the new args.
Definitely interested!