[Chicago-talk] Use vi in perl

[Randal L. Schwartz]

>>>>> "tiger" == tiger peng <tigerpeng2001 at yahoo.com> writes:

tiger> I am trying to use vi as a UI to edit/check dynamic created perl code segment. 
tiger> When user save and quite the vi, the script will check its syntax and force to 
tiger> open the file again if there are any compiling error. I'd like to have the error 
tiger> message show in the new opened vi interface but don't know how to do it. Is here 
tiger> any suggestion?

tiger> Thanks,

tiger> Below is the segment invoke vi and do the check?

tiger> my $msg;
tiger> do {
tiger>   if (defined $msg) {
tiger>     warn "$msg";
tiger>     my $dummy = <STDIN>;
tiger>   }
tiger>   system("/bin/vi",  $tmpfile) == 0 or die $!;
tiger>   $msg = `/usr/bin/perl -c $tmpfile`;
tiger> } while  ($? !=
tiger>   0);_______________________________________________

Maybe something like (untested, but I usually get this right):

    LOOP: {
      system "vi", $tempfile and die "vi exited badly";
      my $pid = open ERRS, "-|";
      die "can't fork: $!" unless defined $pid;
      unless ($pid) { # child does:
        open STDERR, ">&STDOUT"; # merge stderr to stdout
        exec "perl", "-c", $tempfile;
      }
      my $errs;
      $errs .= $_ while <ERRS>;
      close ERRS;
      if ($errs) { # we saw something wrong
        local *ARGV; # prepare for in-place edit
        @ARGV = ($tmpfile);
        while (<>) {
          print;
          ## insert error messages at end of data
          print "\n\n=for COMPILER_ERRORS\n\n$errs\n\n=cut\n\n" if eof;
        }
        redo LOOP;
      }
    } # done

The first person to say "No, you should have used a lexical filehandle
there" will get a free copy of my "Perl Second Best Practices" slide
deck, subtitled "Why Damian's guidelines are just that... guidelines".

-- 
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn at stonehenge.com> <URL:http://www.stonehenge.com/merlyn/>
Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc.
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