[Python-ideas] Suggestion: Clear screen command for the REPL

[João Matos]

Hello,

I don't see why creating a clear command would interfere with dict.clear() 
which is a function/method.

Although my first idea was a clear command, I have no problem if it is a 
clear() function from site.py.

I didn't suggest cls because it is normally used to mean class.

I use Windows and tested a simple (possibly not the best of course) 
solution that seems to work in REPL (but not in IDLE).

import os
import sys

def clear():
    if sys.platform == 'win32':
        os.system('cls')
    else:
        os.system('clear')


Best regards,

JM


segunda-feira, 19 de Setembro de 2016 às 03:33:45 UTC+1, Steven D'Aprano 
escreveu:

> On Sat, Sep 17, 2016 at 11:51:16AM +0100, João Matos wrote: 
> > Hello, 
> > 
> > I would like to suggest adding a clear command (not function) to Python. 
>
> While technically "clear" could be a command, I think it should not be. 
>
> First off, making clear a reserved keyword, and a statement, like print 
> in Python 2, raise or import, would be a major backwards compatibility 
> break. It would mean dict.clear() has to be renamed, and it would break 
> lots of existing code. 
>
> So making clear a keyword is not going to happen. 
>
> If could be a pseudo-built-in, like help(), quit() and exit(), added to 
> built-ins by the site module. In that case, it is *technically* possible 
> to have it operate without the parentheses: 
>
> class ClearType: 
>     def __repr__(self): 
>         # code to clear the screen here 
>         ... 
>
> clear = ClearType() 
>
> so that when you enter clear at the interactive interpreter, __repr__ is 
> called and it clears the screen. But I would argue against it. Instead, 
> it is better to use the same convention that executable code that has 
> side-effects should be implemented as a function call. 
>
> So I suggest following the design of exit() and quit(): 
>
> py> exit 
> Use exit() or Ctrl-D (i.e. EOF) to exit 
>
>
> class ClearType: 
>     def __repr__(self): 
>         return "Use clear() or Ctrl-L (i.e. FF) to clear the screen" 
>     def __call__(self): 
>         # clear screen code goes here 
>
> clear = ClearType()  # or possibly cls ? 
>
>
>
> That is, *if* we add this function at all. 
>
> Personally, I agree with you. There are many different ways of clearing 
> the screen, but they depend on the specific terminal used, whether 
> readline is active or not, the operating system, etc. I think that 
> interactive use is important enough that we should have a standard way 
> of clearing the screen. I personally often find myself just holding down 
> the Enter key until I have a blank screen. 
>
> In this ticket: 
>
> http://bugs.python.org/issue27771 
>
> Raymond Hettinger mentions that it is an often-requested feature by 
> learners, and I believe that IDLE has an active task for this feature: 
>
> http://bugs.python.org/issue6143 
>
> but I don't see any tasks for a clear screen command for the default 
> REPL. 
>
> I'm in favour of adding a clear() *function* to the site.py module, 
> similar to exit/quit/help, but not making it "magical" or a keyword that 
> doesn't require brackets. But I don't know how to implement it for the 
> large variety of terminals and operating systems supported by Python. 
>
> (The fallback if all else fails is easy: get the height of the terminal, 
> in lines, and print that many blank lines.) 
>
>
> -- 
> Steve 
> _______________________________________________ 
> Python-ideas mailing list 
> Python... at python.org <javascript:> 
> https://mail.python.org/mailman/listinfo/python-ideas 
> Code of Conduct: http://python.org/psf/codeofconduct/ 
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20160919/0a9a64a3/attachment.html>