cvs commit: perlfaq perlfaq5.pod perlfaq6.pod

cvsuser     02/09/21 14:04:18

  Modified:    .        perlfaq5.pod perlfaq6.pod
  Log:
  * How do I print to more than one file at once?
       + removed unixist discussion of tee.  Perl has modules to do this now. :)
  
  * How can I read in an entire file all at once?
      + mention File::Slurp
  
  Revision  Changes    Path
  1.26      +13 -21    perlfaq/perlfaq5.pod
  
  Index: perlfaq5.pod
  ===================================================================
  RCS file: /cvs/public/perlfaq/perlfaq5.pod,v
  retrieving revision 1.25
  retrieving revision 1.26
  diff -u -w -r1.25 -r1.26
  --- perlfaq5.pod	5 Sep 2002 00:48:40 -0000	1.25
  +++ perlfaq5.pod	21 Sep 2002 21:04:17 -0000	1.26
  @@ -1,6 +1,6 @@
   =head1 NAME
   
  -perlfaq5 - Files and Formats ($Revision: 1.25 $, $Date: 2002/09/05 00:48:40 $)
  +perlfaq5 - Files and Formats ($Revision: 1.26 $, $Date: 2002/09/21 21:04:17 $)
   
   =head1 DESCRIPTION
   
  @@ -686,30 +686,22 @@
   
   =head2 How do I print to more than one file at once?
   
  -If you only have to do this once, you can do this:
  +To connect one filehandle to several output filehandles,
  +you can use the IO::Tee or Tie::FileHandle::Multiplex modules.
   
  -    for $fh (FH1, FH2, FH3) { print $fh "whatever\n" }
  +If you only have to do this once, you can print individually
  +to each filehandle.
   
  -To connect up to one filehandle to several output filehandles, it's
  -easiest to use the tee(1) program if you have it, and let it take care
  -of the multiplexing:
  -
  -    open (FH, "| tee file1 file2 file3");
  -
  -Or even:
  -
  -    # make STDOUT go to three files, plus original STDOUT
  -    open (STDOUT, "| tee file1 file2 file3") or die "Teeing off: $!\n";
  -    print "whatever\n"                       or die "Writing: $!\n";
  -    close(STDOUT)                            or die "Closing: $!\n";
  -
  -Otherwise you'll have to write your own multiplexing print
  -function--or your own tee program--or use Tom Christiansen's,
  -at http://www.cpan.org/authors/id/TOMC/scripts/tct.gz , which is
  -written in Perl and offers much greater functionality
  -than the stock version.
  +    for $fh (FH1, FH2, FH3) { print $fh "whatever\n" }
   
   =head2 How can I read in an entire file all at once?
  +
  +You can use the File::Slurp module to do it in one step.
  +
  +	use File::Slurp;
  +	
  +	$all_of_it = read_file($filename); # entire file in scalar
  +    @all_lines = read_file($filename); # one line perl element
   
   The customary Perl approach for processing all the lines in a file is to
   do so one line at a time:
  
  
  
  1.17      +28 -28    perlfaq/perlfaq6.pod
  
  Index: perlfaq6.pod
  ===================================================================
  RCS file: /cvs/public/perlfaq/perlfaq6.pod,v
  retrieving revision 1.16
  retrieving revision 1.17
  diff -u -w -r1.16 -r1.17
  --- perlfaq6.pod	20 Jul 2002 17:17:32 -0000	1.16
  +++ perlfaq6.pod	21 Sep 2002 21:04:17 -0000	1.17
  @@ -1,6 +1,6 @@
   =head1 NAME
   
  -perlfaq6 - Regular Expressions ($Revision: 1.16 $, $Date: 2002/07/20 17:17:32 $)
  +perlfaq6 - Regular Expressions ($Revision: 1.17 $, $Date: 2002/09/21 21:04:17 $)
   
   =head1 DESCRIPTION
   
  @@ -147,34 +147,34 @@
   
   =head2 I put a regular expression into $/ but it didn't work. What's wrong?
   
  -$/ must be a string, not a regular expression.  Awk has to be better
  -for something. :-)
  +As of Perl 5.8.0, $/ has to be a string.  This may change in 5.10,
  +but don't get your hopes up. Until then, you can use these examples
  +if you really need to do this.
   
  -Actually, you could do this if you don't mind reading the whole file
  -into memory:
  +Use the four argument form of sysread to continually add to 
  +a buffer.  After you add to the buffer, you check if you have a 
  +complete line (using your regular expression).
   
  -    undef $/;
  -    @records = split /your_pattern/, <FH>;
  +       local $_ = "";
  +       while( sysread FH, $_, 8192, length ) {
  +          while( s/^((?s).*?)your_pattern/ ) {
  +             my $record = $1;
  +             # do stuff here.
  +          }
  +       }
  + 
  + You can do the same thing with foreach and a match using the
  + c flag and the \G anchor, if you do not mind your entire file
  + being in memory at the end.
  +       
  +       local $_ = "";
  +       while( sysread FH, $_, 8192, length ) {
  +          foreach my $record ( m/\G((?s).*?)your_pattern/gc ) {
  +             # do stuff here.
  +          }
  +          substr( $_, 0, pos ) = "" if pos;
  +       }
   
  -The Net::Telnet module (available from CPAN) has the capability to
  -wait for a pattern in the input stream, or timeout if it doesn't
  -appear within a certain time.
  -
  -    ## Create a file with three lines.
  -    open FH, ">file";
  -    print FH "The first line\nThe second line\nThe third line\n";
  -    close FH;
  -
  -    ## Get a read/write filehandle to it.
  -    $fh = new IO::File "+<file";
  -
  -    ## Attach it to a "stream" object.
  -    use Net::Telnet;
  -    $file = new Net::Telnet (-fhopen => $fh);
  -
  -    ## Search for the second line and print out the third.
  -    $file->waitfor('/second line\n/');
  -    print $file->getline;
   
   =head2 How do I substitute case insensitively on the LHS while preserving case on the RHS?