How can I write to Perl filehandles that I stored in array?

Question

I have a list of filenames. I have to create a file for each of those names, write lines to the various files (in no particular order), then close them.

How can I do that in perl? I envision something like the following code (which will not work in that form and give syntax errors):

my @names = qw(foo.txt bar.txt baz.txt);
my @handles;

foreach(@names){
  my $handle;
  open($handle, $_);
  push @handles, $handle; 
}

# according to input etc.:
print $handles[2] "wassup";
print $handles[0] "hello";
print $handles[1] "world";
print $handles[0] "...";

foreach(@handles){
  close $_;
}

How can I do this right?

I suspect this would be better done with references to file handles... but I'm not too keen on file handles in perl. — Ape-inago
– Ape-inago, Commented Jun 9, 2009 at 3:54

ysth · Accepted Answer · 2009-06-09 04:07:02Z

16

The filehandle argument of print must be a bareword, a simple scalar, or a block. So:

print { $handles[0] } ...

This is explained in perldoc -f print. The same restriction applies to indirect object syntax in general, as well as for determining when <> is a readline operation, not a glob operation.

edited Jun 9, 2009 at 4:07

answered Jun 9, 2009 at 3:50

ysth

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Comments

Todd Gardner · Accepted Answer · 2009-06-09 04:00:15Z

3

Here's how I would do it (untested, but I'm pretty sure it is good):

use IO::File;

# ...
my @handles = map { IO::File->new($_, 'w') } @names;

$handles[2]->print("wassup");
# ...

It's OO, it has a cleaner interface, and you don't need to worry about closing them, since it will die when the array goes out of scope.

answered Jun 9, 2009 at 4:00

Todd Gardner

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3 Comments

ysth Over a year ago

die? perhaps you mean "do so". But the example in the question does that too; nothing to do with IO::File.

Todd Gardner Over a year ago

By "die", I meant, the IO::File object would be DESTROYed, which I thought closed the filehandle, but apparently that is just garbage collection, so as long as they are lexically scoped they die anyway.

sds Over a year ago

"-1" for "you don't need to worry about closing them". You always close whatever you open.

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