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Re: input/output parameters

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I wrote:

> I started learning JavaScript but yesterday, but am
> already stuck at implementing input/output parameters.

I have come up with what might be called emulated poiters:

   // Returns JavaScript for the defintion of a "pointer" to a variable named `v':
   // The identifier of the pointer is that of the variable prepended by a $.
   function makeref(v)
   {   return `var $${v} = {set _(val){${v}=val;},get _() {return ${v};}}`;  }

which may be used thus:

   // Calcualtes the square root of `value` and puts it into `$root`.
   // Returns whether the operation has succeeded.
   // In case of an error, stores error message in `$errmsg`.
   function sqrt2
   (   /* in  number */  value, /*  value to take the root of  */
       /* out number */ $root , /* "pointer" to result         */
       /* out string */ $errmsg /* "pointer" to error message  */
   )
   {   if( typeof( value ) !== "number" )
       {   $errmsg._ = "value is not a number.";
           return false;
       }
       if( value < 0 )
       {   $errmsg._ = "value is negative.";
           return false;
       }
       $root._ = Math.sqrt(value);
       return true;
   }

   function test(v)
   {   var /* string */ resmsg;
       var /* number */ root  ; eval( makeref( "root"   ) );
       var /* string */ errmsg; eval( makeref( "errmsg" ) );

       if( sqrt2(v, $root, $errmsg) ) resmsg = `Success: ${root}`;
       else                           resmsg = `Error: ${errmsg}`;
       console.log(`Square root of ${v}: ` + resmsg );
   }

   test("s"  );
   test(-5   );
   test( 1.44);

This code prints:

   Square root of s: Error: value is not a number.
   Square root of -5: Error: value is negative.
   Square root of 1.44: Success: 1.2

Is it possible to define a "macro" in order to simplify the
compilcated expression:

   eval( makeref( "root"   ) )

so that it becomes, say, ref("root")?

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input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-13 15:32 +0300
  Re: input/output parameters Jon Ribbens <jon+usenet@unequivocal.eu> - 2021-03-13 15:16 +0000
    Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-14 18:51 +0300
      Re: input/output parameters Jon Ribbens <jon+usenet@unequivocal.eu> - 2021-03-14 16:15 +0000
        Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-14 18:31 +0000
          Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-14 22:27 +0300
            Re: input/output parameters Jon Ribbens <jon+usenet@unequivocal.eu> - 2021-03-14 23:44 +0000
            Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-15 06:41 -0700
        Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-14 22:17 +0300
          Re: input/output parameters Jon Ribbens <jon+usenet@unequivocal.eu> - 2021-03-14 23:28 +0000
          Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-15 06:39 -0700
      Re: input/output parameters Ben Bacarisse <ben.usenet@bsb.me.uk> - 2021-03-14 22:32 +0000
      Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-15 06:36 -0700
        Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-20 14:49 +0300
          Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-20 11:59 -0700
            Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-20 13:07 -0700
          Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-20 19:29 +0000
            Re: input/output parameters Jon Ribbens <jon+usenet@unequivocal.eu> - 2021-03-20 20:35 +0000
  Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-15 00:27 +0300
    Re: input/output parameters Jon Ribbens <jon+usenet@unequivocal.eu> - 2021-03-14 23:51 +0000
      Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-20 14:56 +0300
        Re: input/output parameters Jon Ribbens <jon+usenet@unequivocal.eu> - 2021-03-20 15:08 +0000
          Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-21 15:16 +0300
            Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-21 08:46 -0700
              Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-04-10 14:54 +0300
        Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-20 12:05 -0700
          Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-21 15:58 +0300
    Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-15 06:43 -0700
    Re: input/output parameters Silvio <silvio@internet.com> - 2021-03-15 18:01 +0100
      Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-16 18:06 +0000
        Re: input/output parameters Silvio <silvio@internet.com> - 2021-03-16 23:58 +0100
          Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-17 19:14 +0000
            Re: input/output parameters Silvio <silvio@internet.com> - 2021-03-17 23:46 +0100
              Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-18 18:04 +0000
                Re: input/output parameters Silvio <silvio@internet.com> - 2021-03-22 00:39 +0100
                Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-23 10:44 +0000
                Re: input/output parameters Silvio <silvio@internet.com> - 2021-03-30 00:33 +0200
                Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-31 19:53 +0100
                Re: input/output parameters Silvio <silvio@internet.com> - 2021-04-01 01:17 +0200
                Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-04-01 18:02 +0100
      Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-20 15:50 +0300
        Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-20 18:52 +0000
          Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-21 17:35 +0300
            Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-21 08:50 -0700
              Re: input/output parameters Anton Shepelev <anton.txt@gmail.com> - 2021-03-21 19:31 +0300
            Re: input/output parameters John G Harris <niam@jghnorth.org.uk.invalid> - 2021-03-21 19:27 +0000
        Re: input/output parameters "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2021-03-20 13:02 -0700
  Re: input/output parameters Postiljon Petskin <yyyyyyyyyyyywwwww@zohomail.eu> - 2023-04-22 08:47 -0700

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