Print itself

Revision as of 19:13, 8 June 2020 by rosettacode>Gerard Schildberger (→‎{{header|REXX}}: added the REXX computer programming language for this task.)

Create a program, which prints it's source code to the stdout!

Print itself is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

DO NOT USE the source file of the program! It is the running program itself which has to contain it's source code somewhow, whitout reading the source file!

Furor

A very short solution, using some special features of Furor: <lang Furor> "#s sto selfstring QUOTE @selfstring dup print QUOTE NL printnl end { „selfstring” }"

  1. s sto selfstring QUOTE @selfstring dup print QUOTE NL printnl end { „selfstring” }

</lang> And behold, here is a more complex but "traditional" solution of this famous task, solved by 3 loops: <lang Furor>

  1. g §vége §eleje - tokensize / sto maxlines
  2. s

7 {| {} §eleje[] printnl |}

 @maxlines {|  {} §eleje[] QUOTE print QUOTE NL |}

7 @maxlines {|| {} §eleje[] printnl |} end eleje: "#g §vége §eleje - tokensize / sto maxlines" "#s" "7 {| {} §eleje[] printnl |}" " @maxlines {| {} §eleje[] QUOTE print QUOTE NL |}" "7 @maxlines {|| {} §eleje[] printnl |}" "end" "eleje:" "vége:" "{ „selfstring” }" "{ „maxlines” }" vége: { „selfstring” } { „maxlines” } </lang>

Go

<lang go>package main

import (

   "fmt"
   "io/ioutil"
   "log"
   "os"
   "path"

)

func main() {

   self := path.Base(os.Args[0]) + ".go"
   bytes, err := ioutil.ReadFile(self)
   if err != nil {
       log.Fatal(err)
   }
   fmt.Print(string(bytes))

}</lang>

Output:

Just the invoking line as remainder is, of course, as above.

$ go run self_print.go

REXX

<lang rexx>/*REXX program prints its own multi─line source to the standard output (stdout). */

   do j=1  for sourceline()
   call lineout , sourceline(j)
   end   /*j*/                                  /*stick a fork in it,  we're all done. */</lang>

Wren

<lang ecmascript>import "os" for Process import "io" for File

var args = Process.allArguments System.write(File.read(args[1]))</lang>

Output:

Just the invoking line as remainder is, of course, as above.

$ wren self_print.wren