Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!apple!veritas!amdcad!sono!porky!mayer
From: mayer@sono.uucp (Ronald &)
Newsgroups: comp.lang.perl
Subject: using perl interactively
Message-ID: <MAYER.91May21115429@porky.sono.uucp>
Date: 21 May 91 18:54:29 GMT
Sender: mayer@sono.uucp (Ronald Mayer)
Distribution: comp
Organization: Acuson; Mountain View, California
Lines: 34


Has anyone written a good interface for using perl interactively?
(kinda like a over-featured calculator with string and array
operators, and access to unix commands and system calls)

I guess what I'm looking for is something like this:

  #!/usr/local/bin/perl
  $|=1;                                          # good in interactive programs
  $nprompt = ">";                                # normal prompt
  $cprompt = ">>";			         # continuation prompt
  while(1) {
      print "$input",$input?$cprompt:$nprompt;   # print the prompt
      $input  .= <>;                             # get or append to input
      $_ = @_ = eval $input;                     # eval input
      if      (!($@)) {                          # success
	  print  "@_\n";			 # show result of eval
      } elsif ($@ =~ /syntax error in file \(eval\) at line [0-9]+, at EOF/) {
	  next;                                  # probably continued statement
      } else {                                   # probably syntax error
	  print $@;                              # show eval error message
      }
      undef($input);                             # clear input
  }


which seems to do fine for all one line statements and many (but
probably not most) multi-line commands like while loops.  Is there a
better way of guessing whether a failed eval failed because of a 'real'
syntax error or if the string being eval'd is a potentially legal but
incomplete perl statement?

    Ron Mayer
    mayer@sono.uucp   sun!sono!mayer