Hash values as filehandles

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

Why doesn't the print command take a hash value as a file handle? This has always been an annoyance for me:

my %fh;
while(<>) {
   my @record = split;
   $fh{$record[0]} || open($fh{$record[0]});
   my $fh = $fh{$record[0]};
   print $fh $_;
}
[download]

When I try to use $fh{$record[0]} directly, perl complains about syntax errors. My work around works, but I somehow feel dirty afterwards. Is there something that I'm missing?

Thanks in advance,
thor

Comment on Hash values as filehandles Download Code

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Re: Hash values as filehandles by jmcnamara (Monsignor) on Apr 30, 2004 at 18:41 UTC
To use a hash value as a filehandle you need to add another set of braces to create a block around it: `print {$fh{$record[0]}} $_;` [download] See print in perlfunc. -- John.	[reply] [d/l]
Re: Hash values as filehandles by chromatic (Archbishop) on Apr 30, 2004 at 18:57 UTC
Why doesn't the print command take a hash value as a file handle? It's very difficult for the parser to know at compile time what the hash value will be. If it's a file handle, you probably want to print to it. If it's not a file handle, you probably want to print it. It's probably fixable, but the implications might be kinda scary.	[reply]
Re: Hash values as filehandles by blue_cowdawg (Monsignor) on Apr 30, 2004 at 18:42 UTC
Is there something that I'm missing? Looking at your code I'm somewhat perplexed by what you are trying to do since I don't know what's in what variable. If `$record[0]` is supposed to be a file name you might want to consider trying something like: `use FileHandle; : : hand waving like crazy here.. $fh{record[0]}=new FileHandle $record[0],"r" or die $!; : :` [download] or some such.	[reply] [d/l] [select]
Re: Hash values as filehandles by ysth (Canon) on Apr 30, 2004 at 21:19 UTC
The file handle for print goes in what is known as the "indirect object" slot, and follows the requirements for an object: either a simple var (or bareword) or a BLOCK: `print {$fh{record[0]}} $_;` [download]	[reply] [d/l]