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I'm pretty new to Python. I'm trying to modify a script so it will run in an infinite loop, will get commands from the console and will act according to the commands I defined.

I'm talking about something that can do the following example:

Shell> myconsole.py
> h
Usage: [set_param1 [a1 [a2...]]] [set_param2 [b1 [b2...]]] [send_params]
> set_param1 4
> set_param2 5 6
> send_params
Parameters sent successfully!
> quit
Shell>

I tried using argpars but I have several issues with it:
1. It doesn't work properly if I don't have at least one arg with '-'
2. When I call help ('h'/'help') or put a bad arg, it shows the help and get stuck. I want it to go back to the infinite loop and wait for more commands.

I've read the thread: how to make a Command Line Interface or Interpreter in python
It wasn't really helpful.

Can anyone help please?

Thanks,
Gur

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  • 2
    Write a subclass of cmd.Cmd Commented Feb 12, 2014 at 10:06

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How to make a Command Line Interpreter in python?

No idea how to do it in Python, but i can tell you how to write a small interpreter from YOURS language to BATCH.

First how will it work: You type in file something, a code like: _display = Hello World! and the interpreter will convert it to echo Hello World!

So it is needed ONLY a replace Code. So thats it:

type %name%|repl "_display =" "echo" >compiler.log
move /y compiler.log %name%

And the Latest line:

type %name%|repl "a code statement" "translation" >compiler.log
move /y compiler.log %name%.**bat**

The %name% is just a variable, you can replace it by File Name or Ask for filename the user by typing

set/p name="Name Of Project: "

So and thats it! You can write own programming language just in BATCH Language! BATCH Language also in Notepad, requires no compiler.

Wait! You need a REPL File! Copy THIS:

@if (@X)==(@Y) @end /* Harmless hybrid line that begins a JScript comment
@echo off
if .%2 equ . (
  if "%~1" equ "/?" (
    <"%~f0" cscript //E:JScript //nologo "%~f0" "^:::" "" a
    exit /b 0
  ) else if /i "%~1" equ "/?regex" (
    explorer "http://msdn.microsoft.com/en-us/library/ae5bf541(v=vs.80).aspx"
    exit /b 0
  ) else if /i "%~1" equ "/?replace" (
    explorer "http://msdn.microsoft.com/en-US/library/efy6s3e6(v=vs.80).aspx"
    exit /b 0
  ) else if /i "%~1" equ "/V" (
    <"%~f0" cscript //E:JScript //nologo "%~f0" "^::(REPL\.BAT version)" "$1" a
    exit /b 0
  ) else (
    call :err "Insufficient arguments"
    exit /b 2
  )
)
echo(%~3|findstr /i "[^SMILEBVXAJ]" >nul && (
  call :err "Invalid option(s)"
  exit /b 2
)
echo(%~3|findstr /i "M"|findstr /i "A"|findstr /vi "S" >nul && (
  call :err "Incompatible options"
  exit /b 2
)
cscript //E:JScript //nologo "%~f0" %*
exit /b %errorlevel%

:err
>&2 echo ERROR: %~1. Use REPL /? to get help.
exit /b

************* JScript portion **********/
var rtn=1;
try {
  var env=WScript.CreateObject("WScript.Shell").Environment("Process");
  var args=WScript.Arguments;
  var search=args.Item(0);
  var replace=args.Item(1);
  var options="g";
  if (args.length>2) options+=args.Item(2).toLowerCase();
  var multi=(options.indexOf("m")>=0);
  var alterations=(options.indexOf("a")>=0);
  if (alterations) options=options.replace(/a/g,"");
  var srcVar=(options.indexOf("s")>=0);
  if (srcVar) options=options.replace(/s/g,"");
  var jexpr=(options.indexOf("j")>=0);
  if (jexpr) options=options.replace(/j/g,"");
  if (options.indexOf("v")>=0) {
    options=options.replace(/v/g,"");
    search=env(search);
    replace=env(replace);
  }
  if (options.indexOf("x")>=0) {
    options=options.replace(/x/g,"");
    if (!jexpr) {
      replace=replace.replace(/\\\\/g,"\\B");
      replace=replace.replace(/\\q/g,"\"");
      replace=replace.replace(/\\x80/g,"\\u20AC");
      replace=replace.replace(/\\x82/g,"\\u201A");
      replace=replace.replace(/\\x83/g,"\\u0192");
      replace=replace.replace(/\\x84/g,"\\u201E");
      replace=replace.replace(/\\x85/g,"\\u2026");
      replace=replace.replace(/\\x86/g,"\\u2020");
      replace=replace.replace(/\\x87/g,"\\u2021");
      replace=replace.replace(/\\x88/g,"\\u02C6");
      replace=replace.replace(/\\x89/g,"\\u2030");
      replace=replace.replace(/\\x8[aA]/g,"\\u0160");
      replace=replace.replace(/\\x8[bB]/g,"\\u2039");
      replace=replace.replace(/\\x8[cC]/g,"\\u0152");
      replace=replace.replace(/\\x8[eE]/g,"\\u017D");
      replace=replace.replace(/\\x91/g,"\\u2018");
      replace=replace.replace(/\\x92/g,"\\u2019");
      replace=replace.replace(/\\x93/g,"\\u201C");
      replace=replace.replace(/\\x94/g,"\\u201D");
      replace=replace.replace(/\\x95/g,"\\u2022");
      replace=replace.replace(/\\x96/g,"\\u2013");
      replace=replace.replace(/\\x97/g,"\\u2014");
      replace=replace.replace(/\\x98/g,"\\u02DC");
      replace=replace.replace(/\\x99/g,"\\u2122");
      replace=replace.replace(/\\x9[aA]/g,"\\u0161");
      replace=replace.replace(/\\x9[bB]/g,"\\u203A");
      replace=replace.replace(/\\x9[cC]/g,"\\u0153");
      replace=replace.replace(/\\x9[dD]/g,"\\u009D");
      replace=replace.replace(/\\x9[eE]/g,"\\u017E");
      replace=replace.replace(/\\x9[fF]/g,"\\u0178");
      replace=replace.replace(/\\b/g,"\b");
      replace=replace.replace(/\\f/g,"\f");
      replace=replace.replace(/\\n/g,"\n");
      replace=replace.replace(/\\r/g,"\r");
      replace=replace.replace(/\\t/g,"\t");
      replace=replace.replace(/\\v/g,"\v");
      replace=replace.replace(/\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4}/g,
        function($0,$1,$2){
          return String.fromCharCode(parseInt("0x"+$0.substring(2)));
        }
      );
      replace=replace.replace(/\\B/g,"\\");
    }
    search=search.replace(/\\\\/g,"\\B");
    search=search.replace(/\\q/g,"\"");
    search=search.replace(/\\x80/g,"\\u20AC");
    search=search.replace(/\\x82/g,"\\u201A");
    search=search.replace(/\\x83/g,"\\u0192");
    search=search.replace(/\\x84/g,"\\u201E");
    search=search.replace(/\\x85/g,"\\u2026");
    search=search.replace(/\\x86/g,"\\u2020");
    search=search.replace(/\\x87/g,"\\u2021");
    search=search.replace(/\\x88/g,"\\u02C6");
    search=search.replace(/\\x89/g,"\\u2030");
    search=search.replace(/\\x8[aA]/g,"\\u0160");
    search=search.replace(/\\x8[bB]/g,"\\u2039");
    search=search.replace(/\\x8[cC]/g,"\\u0152");
    search=search.replace(/\\x8[eE]/g,"\\u017D");
    search=search.replace(/\\x91/g,"\\u2018");
    search=search.replace(/\\x92/g,"\\u2019");
    search=search.replace(/\\x93/g,"\\u201C");
    search=search.replace(/\\x94/g,"\\u201D");
    search=search.replace(/\\x95/g,"\\u2022");
    search=search.replace(/\\x96/g,"\\u2013");
    search=search.replace(/\\x97/g,"\\u2014");
    search=search.replace(/\\x98/g,"\\u02DC");
    search=search.replace(/\\x99/g,"\\u2122");
    search=search.replace(/\\x9[aA]/g,"\\u0161");
    search=search.replace(/\\x9[bB]/g,"\\u203A");
    search=search.replace(/\\x9[cC]/g,"\\u0153");
    search=search.replace(/\\x9[dD]/g,"\\u009D");
    search=search.replace(/\\x9[eE]/g,"\\u017E");
    search=search.replace(/\\x9[fF]/g,"\\u0178");
    if (options.indexOf("l")>=0) {
      search=search.replace(/\\b/g,"\b");
      search=search.replace(/\\f/g,"\f");
      search=search.replace(/\\n/g,"\n");
      search=search.replace(/\\r/g,"\r");
      search=search.replace(/\\t/g,"\t");
      search=search.replace(/\\v/g,"\v");
      search=search.replace(/\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4}/g,
        function($0,$1,$2){
          return String.fromCharCode(parseInt("0x"+$0.substring(2)));
        }
      );
      search=search.replace(/\\B/g,"\\");
    } else search=search.replace(/\\B/g,"\\\\");
  }
  if (options.indexOf("l")>=0) {
    options=options.replace(/l/g,"");
    search=search.replace(/([.^$*+?()[{\\|])/g,"\\$1");
    if (!jexpr) replace=replace.replace(/\$/g,"$$$$");
  }
  if (options.indexOf("b")>=0) {
    options=options.replace(/b/g,"");
    search="^"+search
  }
  if (options.indexOf("e")>=0) {
    options=options.replace(/e/g,"");
    search=search+"$"
  }
  var search=new RegExp(search,options);
  var str1, str2;

  if (srcVar) {
    str1=env(args.Item(3));
    str2=str1.replace(search,jexpr?replFunc:replace);
    if (!alterations || str1!=str2) if (multi) {
      WScript.Stdout.Write(str2);
    } else {
      WScript.Stdout.WriteLine(str2);
    }
    if (str1!=str2) rtn=0;
  } else if (multi){
    var buf=1024;
    str1="";
    while (!WScript.StdIn.AtEndOfStream) {
      str1+=WScript.StdIn.Read(buf);
      buf*=2
    }
    str2=str1.replace(search,jexpr?replFunc:replace);
    WScript.Stdout.Write(str2);
    if (str1!=str2) rtn=0;
  } else {
    while (!WScript.StdIn.AtEndOfStream) {
      str1=WScript.StdIn.ReadLine();
      str2=str1.replace(search,jexpr?replFunc:replace);
      if (!alterations || str1!=str2) WScript.Stdout.WriteLine(str2);
      if (str1!=str2) rtn=0;
    }
  }
} catch(e) {
  WScript.Stderr.WriteLine("JScript runtime error: "+e.message);
  rtn=3;
}
WScript.Quit(rtn);

function replFunc($0, $1, $2, $3, $4, $5, $6, $7, $8, $9, $10) {
  var $=arguments;
  return(eval(replace));
}

.. and save to a BATCH (.bat) File named "repl.bat"

~whispereq 2017

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