typglobs and filehandles

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

I'm having a hard time successfully writing to filehandles stores in variables. here's how it goes:

# 
# open report files for printing
my $filepath = "/usr/openv/scripts";

open *NTOUT,    ">>$filepath/nt.html" or die "cannot open nt file for 
+writing: $!\n";
open *UNIXOUT,  ">>$filepath/unix.html" or die "cannot open unix file 
+for writing: $!\n";
open *MAILOUT,  ">>$filepath/mail.html" or die "cannot open mail file 
+for writing: $!\n";

#
# some unrelated code ......
#
foreach my $class ( sort keys %classHash ) {

        if  ( $classHash{$class} = "NT" )   { $outhandle = *NTOUT; }
        if  ( $classHash{$class} = "UNIX" ) { $outhandle = *UNIXOUT; }
        if  ( $classHash{$class} = "MAIL" ) { $outhandle = *MAILOUT; }

    foreach my $status ( sort keys %{ $classHash{$class} } ) {

        if ( $status eq "success" ) {

            print $outhandle <<SUC;
        <table border=1 width="100%">
        <tr>
          <td colspan="12" align="left" valign="center" bgcolor="#33cc
+33">
           <b><font size="+1">$class:  Successful Jobs</b></font>
          </td>
        </tr>
SUC
[download]

...the print statement print $outhandle (as well as subsequent others) don't actually print to the filehandle. The problem is not with %classHash; I've checked that it is being populated as I expect. But, if I do this:

@fh = ( *NTOUT,*UNIXOUT, *MAILOUT );
foreach (@fh) {
print $_ <<EOC;
<html>
  <head>
    <title>[Backup report] $humanstart - $humanstop</title>
  </head>

  <body bgcolor="#ffffff">

  <h2 align="left">Daily Backup Report</h2>
  <h3 align="left">From $humanstart to $humanstop</h3>
EOC

}
[download]

It does print to each filehandle. What am I doing wrong, here?

Comment on typglobs and filehandles Select or Download Code

Replies are listed 'Best First'.
Re: typglobs and filehandles by panix (Monk) on Jul 23, 2002 at 03:28 UTC
Are you sure it's not the contents of %classHash? Your code seems to work just fine (eg, the snippet below works). `open(TEST, ">>test.html") \|\| die; my $outhandle = undef; $outhandle = *TEST; print $outhandle "test\n"; close($outhandle);` [download] If you replace the consecutive classHash tests with an if/elsif/else die, you should catch this.	[reply] [d/l]
Re: typglobs and filehandles by zejames (Hermit) on Jul 23, 2002 at 03:28 UTC
Hi Your mistake must be here : `foreach my $class ( sort keys %classHash ) { if ( $classHash{$class} = "NT" ) { $outhandle = NTOUT; } if ( $classHash{$class} = "UNIX" ) { $outhandle = UNIXOUT; } if ( $classHash{$class} = "MAIL" ) { $outhandle = MAILOUT; } foreach my $status ( sort keys %{ $classHash{$class} } ) {` [download] `$classHash{$class}` cannot be a string, as you seem to consider, for example, in `if ( $classHash{$class} = "MAIL" )` AND* a hash reference, like it is used in `foreach my $status ( sort keys %{ $classHash{$class} } ) {` So `$status` is never success, and you never write anything. Moreover, you must use `eq` to compare two strings. And `==` (and not `=`) to compare to numbers. BTW, you `use strict; use warnings;` do you ? HTH -- zejames	[reply] [d/l] [select]
Re: typglobs and filehandles by Zaxo (Archbishop) on Jul 23, 2002 at 03:30 UTC
In your `$outhandle` assignments, use references to typeglobs as filehandles, as in: `perl -e 'my $foo = \*STDOUT; print $foo "Foo!$/"'` [download] Why don't you leave the files closed till you know which you need? Then you could pick the correct filename instead and open only that. `my %platfile = ( NT => 'nt.html', UNIX => 'unix.html', MAIL => 'mail.html' ); #... { open my $out, '>>', "$filepath/$platfile{$classHash{$class}}" or die $!; # ... }` [download] At that point, we run into another problem with your code. What is in `%classHash`? You iterate through all the keys twice - nested. Surely that's not what you should be doing. After Compline, Zaxo	[reply] [d/l] [select]
Re: typglobs and filehandles by Ionitor (Scribe) on Jul 23, 2002 at 03:18 UTC
Well, are you sure that print is ever being run? And it it is, does it print to MAILOUT each time? Here's your problem: `if ( $classHash{$class} = "NT" )` [download] You're missing an equals sign, as right now you assign to `$classHash{$class}` three times. I suspect that fixing that problem will help you a lot. To avoid this in the future, you might want to write: `if ( "NT" == $classHash{$class})` [download] since you can't assign to a constant string, so only having one equals sign gives you an error. BTW, your syntax for printing to a filehandle assigned to a scalar appears correct--at least, it works for me.	[reply] [d/l] [select]


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