in reply to Getting at a hash from its values

Here's one way of doing what you're asking for. Note that if you try to get an index for a child_fh value that does not exist, this method will die() on you (purposely). 

my @hashes = (
    { child_fh => $obj1 },
    { child_fh => $obj2 }
);

my @readable = $s->can_read(1);
for (@readable) {
    my $index = -1;
    while (++$index > -1) {
        last if ($hashes[$index]{child_fh} == $_);
        die("object not found in $hashes!\n")
            if ($index == $#hashes);
    );

    # $index now contains your array index, '3' or '5'
    # from your example.
    print $hashes[$index]{child_fh}, "\n";
}

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Re^2: Getting at a hash from its values
by ikegami (Patriarch) on Mar 01, 2006 at 05:54 UTC
    The following two snippets are a bit easier to read: 
    my @readable = $s->can_read(1);
for my $fh (@readable) {
    my ($index) = grep { $hashes[$_]{child_fh} == $fh } 0..$#hashes;

    die("object not found in \$hashes!\n")
       if not defined $index;

    ...
}

    [download]

    and 

    use List::Util qw( first );

my @readable = $s->can_read(1);
for my $fh (@readable) {
    my $index = first { $hashes[$_]{child_fh} == $fh } 0..$#hashes;

    die("object not found in \$hashes!\n")
       if not defined $index;

    ...
}

    [download]
    Or if you don't need the index, just the object in @hashes: 
    my @readable = $s->can_read(1);
for my $fh (@readable) {
    my ($obj) = grep { $_->{child_fh} == $fh } @hashes
       or die("object not found in \$hashes!\n");

    ...
}

    [download]

    and 

    use List::Util qw( first );

my @readable = $s->can_read(1);
for my $fh (@readable) {
    my $obj = first { $_->{child_fh} == $fh } @hashes
       or die("object not found in \$hashes!\n");

    ...
}

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