printing to filehandle contained in a hash

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

Trying to print to a filehandle that is stored in a hash, but I get this error when I try to print to it: Can't use string ("GLOB(0x9547728)") as a symbol ref while "strict refs"

while (my ($fileh, $repoch) = each(%radar)){
        if ($ltgepoch == $repoch) {
            if ($temp[3] eq "") {
                print $fileh "$temp[2],$temp[4],@date,@time\n";
                print "$temp[0] $temp[1] $temp[2] $temp[4]\n";
            }
            elsif ($temp[4] eq "") {
                print $fileh "$temp[2],$temp[3],@date,@time\n";
                print "$temp[0] $temp[1] $temp[2] $temp[3]\n";
            }
        }
    }
[download]

Ideas?

Comment on printing to filehandle contained in a hash Download Code

Replies are listed 'Best First'.
Re: printing to filehandle contained in a hash by ikegami (Patriarch) on Feb 20, 2010 at 01:44 UTC
The pattern you are using, `while (my ($fileh, $repoch) = each(%radar)){ if ($ltgepoch == $repoch) { ... } }` [download] defies the entire purpose of using a hash. The above should be `if (exists($radar{$ltgepoch})) { ... }` [download] which means your keys and your values are backwards. Switch them around and it also solves the problem you asked about.	[reply] [d/l] [select]
Re: printing to filehandle contained in a hash by jethro (Monsignor) on Feb 20, 2010 at 01:17 UTC
You can store a filehandle as hash value, but you can't store it as hash key. As key the filehandle gets stringified and loses any special properties `#!/usr/bin/perl use warnings; use strict; my %f; open($f{r},'>','test.txt') or die; my $fhvalue=$f{r}; print '<',ref $fhvalue,">\n"; my %i; $i{$fhvalue}= 1; my ($fhkey)= keys %i; print '<',ref $fhkey,">\n"; #prints <GLOB> <>` [download] UPDATED with the code example	[reply] [d/l]
Re: printing to filehandle contained in a hash by rubasov (Friar) on Feb 20, 2010 at 01:18 UTC
All of your hash keys (just the keys, not the values) will be stringified in perl5, so you cannot store a filehandle (or a reference) in a hash key (a hash key is a string, not a scalar variable for general use). Try to store these somewhere else, depending on your data structure for instance: `%radar = (some_id => [$fileh, $repoch], some_other_id => [$fileh2, $re +poch2], ...)` [download]	[reply] [d/l]
Re: printing to filehandle contained in a hash by crashtest (Curate) on Feb 20, 2010 at 01:39 UTC
Hash keys are stringified. When you used the file handle reference as hash key, `perl` turned it into a string representation of the reference. The reference itself is gone! Perhaps a hash wasn't the right choice for your data structure. Since all you're doing is iterating over your data anyway, perhaps an array of arrays (AoA) would be more useful. Untested: `# Somewhere earlier... my @radar = (); push @radar, [$fileh, $repoch] for (1..5); # ... then: for (@radar){ my ($fileh, $repoch) = @$_; # ... continue as before. }` [download]	[reply] [d/l] [select]


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