Is there a simple way to close this file that works?

Show us how you assigned a file handle to that hash...

    open   $files{ "foo" }, "  > xyz";
    print  { $files{ "foo" } } "done\n";
    close  *{ $files{ "foo" } };
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I would love to understand why , though. It is not obvious to me from the documentation.

Because it is documented that way :) in print :)

See also Re: Split output by tabs (Perl Best Practices #136: Always put filehandles in braces within any print -- bogus "rule" )

The Perl print function, which has a long history and a tricky syntax, takes an optional file handle as its first argument. Without the optional first file handle argument, it prints to the default output handle (typically STDOUT). Moreover, it has a special syntax where its first and second arguments are separated not by a comma (like most Perl functions) but by a space! And because your first argument to print is more complex than a plain scalar variable, you need to specify it in a bare block, for, erm, historical reasons. Note that this special block syntax to print is clearly documented:

If you're storing handles in an array or hash, or in general whenever you're using any expression more complex than a bareword handle or a plain, unsubscripted scalar variable to retrieve it, you will have to use a block returning the filehandle value instead

However, you then made the (perfectly understandable) "mistake" of assuming that this special print syntax applies to other Perl functions, such as close. When calling most Perl functions, you should not place the first function argument in a block; this is a one-off special case for the print function.

You need to lose the braces around the argument to close because Perl is interpreting that as an anonymous hash (as "use warnings" will tell you). This works for me:

use strict;
use warnings;
my %files;
open $files{"foo"}, '>', "xyz"   or die "open failed: $!";
print { $files{"foo"} } "done\n" or die "print failed: $!";
# close { $files{"foo"} };    # oops: 'Odd number of elements in anony
+mous hash'
close $files{"foo"};          # works ok
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Try this:

use IO::File;

my %files;
$files{"foo"} = IO::File->new(">xyz");
print { $files{"foo"} } "done\n";
$files{"foo"}->close;

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