#!perl -w
use strict;

sub my_func {
    print @_;
}

my %hash = (
"my_function" => \&my_func
);

my $func_ref = $hash{"my_function"};

&$func_ref("bla");
[download]

Had you posted a working code snipped, chances are you'd have found out for yourself ;-)

I strongly advise you use strictures (use strict; use warnings;) which would have told you about the syntax error in my $func_ref = %hash{"my_function"};. Using & to call a sub is somewhat out of favor. The following may get you sorted out:

use strict;
use warnings;

my %hash = (hello => "Hello World\n", my_function => \&my_func);
my $funcref = $hash{my_function};

&$funcref (\%hash);
$funcref->(\%hash);

sub my_func {
    my $hashref = shift;
    
    print $hashref->{hello}
}
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Prints:

Hello World
Hello World
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That can't be the cause of the problem, since %hash{"my_func"} is a compile time syntax error, not a runtime error like "can't use '1'" ..." in your original post.

update: at least it is in current perl (5.8.8) it might be different in old(er) perls.

"What should it profit a man, if he should win a flame war, yet lose his cool?"

Yep, it should have been $hash{"my_function"}.

I get:

syntax error at noname.pl line 2, near "%hash{"
Execution of noname.pl aborted due to compilation errors.
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with:

my %hash = (hello => "Hello World\n", my_function => \&my_func);
my $func_ref = %hash{"my_function"};

$func_ref-> (\%hash);

sub my_func {
    my $hashref = shift;
    
    print $hashref->{hello}
}
[download]

so it seems the sample code you provided is not quite the same as the code you tested, or there is a Perl version difference issue perhaps? (I'm using AS Perl v5.8.7)

---

DWIM is Perl's answer to Gödel