如何为Perl的File :: Fetch设置输出文件？

Question

I am using File::Fetch in a Perl script. How can I get File::Fetch to store a file to be downloaded in a specified file?

I have tried:

    use File::Fetch;
    my $ff = File::Fetch->new(uri => 'http://stackoverflow.com/users/63550');
    #my $where = $ff->fetch() or die $ff->error; # Creates a file named "63550".
    my $where = $ff->fetch(to => 'SO.html'); # Creates a subfolder named SO.html with a file named "63550" in it.

A workaround would be to rename the file after download, but is it possible to specify the file name immediately?

Test platform:

• ActiveState Perl 64 bit. From perl -v :

   v5.10.0 built for MSWin32-x64-multi-thread Binary build 1004 [287188] provided by ActiveState. 

• Windows XP.

Answer 1

Looking at the source code, the only way seems to be making a subclass and overriding the output_file method. I guess the author would accept a patch that makes output_file a read/write property, so that it can be changed at run-time.

Answer 2

I looked at the File::Fetch 0.22 code to see what you would need to do for this. There's a bug that prevents you from subclassing (unless you want to override new() and create() to fix it). Update The File::Fetch developers have applied my patch and a new release should be out shortly.

The easiest thing is probably to fetch the file to a temporary directory, discover the name with output_file , and rename it to its final location.

Lukáš thinks I'm wrong, but I don't think he's actually tried it like I had. Creating a subclass and overriding output_file has no effect:

#!perl

use strict;
use warnings;

BEGIN {
package File::Fetch::MyOutput;
use parent qw(File::Fetch);

sub output_file { die "I was called!" }
}

my $ff = File::Fetch::MyOutput->new( 
     uri => 'http://search.cpan.org/~bingos/File-Fetch-0.22/lib/File/Fetch.pm' 
     );

$ff->fetch( to => '.' );

When I run this, I end up with Fetch.pm in the current directory. The script does not die because it never invoked my output_file because the object is not actually in my subclass. This is a bug in File::Fetch which I've filed as RT 53427 .