Looping through an array of objects

dalziel has asked for the wisdom of the Perl Monks concerning the following question:

I'm using the XML::FOAF parser to grab lists of links from a site. It creates the object ok, but when I get the 'knows' array, which is an array of all the people this person knows, I can't seem to loop through the array:

my $foaf = XML::FOAF->new(URI->new('http://glenn.typepad.com/foaf.rdf'
+));
my $person = $foaf->person;
my @people = $person->knows;
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If I say print $people[0][0]->name; it prints out the name of the first person, but

foreach (@people[0)
{
    print $_;
}
[download]

doesn't print out the names of all the people, it just seems to return person as itself (ie if I put

    my @pp = $_;
    print $pp[0][0]->name;
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inside the loop it works) I'm not sure why it needs the array of array ($people[0][0]) but I've tried it without that & it doesn't work. Am I missing something blindingly obvious here?

Comment on Looping through an array of objects Select or Download Code

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Re: Looping through an array of objects by graff (Chancellor) on Jan 19, 2004 at 02:25 UTC
If this works: `print $people[0][0]->name;` [download] then looping would work like this: `foreach ( @{$people[0]} ) { print $_->name; }` [download] Or you could do it like this: `foreach $row ( @people ) { foreach $cell ( @$row ) { print $cell->name; } }` [download] The point is that each element in @people is itself an array reference, and needs to be treated as such. In the first example, in order to dereference an element of @people as an array, you need the curly braces between the "@" and the expression that represents the array ref. In the second example, doing the dereferencing in two stages makes the syntax less messy. At each iteration of the outer loop, $row is set to the array ref for the inner dimension of @people, and is easier to dereference.	[reply] [d/l] [select]
Re: Re: Looping through an array of objects by dalziel (Initiate) on Jan 19, 2004 at 02:44 UTC
Thankyou, you've saved me a lot of trouble. It would apear that I missed the "Returns a reference to an array" in the CPAN doco. /slaps forehead	[reply]