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Hi,

I am a complete beginner I tried to find some information on the
topic, however, I have only found how to deal with arrays and
associative arrays. All documentation seems to be helpless with an
object/structure.

I have a fixed structure like this (comes from external file):

$self->{data} = {
'ver' => 2,
'list' => {
'name1' => 'item1',
'different_name' => 'another_item',
'whatever' => 'special_item',
# and 1000 more
}
};
I need a content of $self->{data}->{list}. I do knot know field names
nor keys.
There is probably some simple loop, foreach or while,e.g.
( ($c,$v) = each %self->{data}->{list} ).
But I cannot figure out the details that would finally let it work.
Help...

Mafj <> writes:

> I have a fixed structure like this (comes from external file):
>
> $self->{data} = {
> 'ver' => 2,
> 'list' => {
> 'name1' => 'item1',
> 'different_name' => 'another_item',
> 'whatever' => 'special_item',
> # and 1000 more
> }
> };
> I need a content of $self->{data}->{list}. I do knot know field names
> nor keys.
> There is probably some simple loop, foreach or while,e.g.
> ( ($c,$v) = each %self->{data}->{list} ).

You're pretty close. To begin with, since $self->{data}->{list} is a
reference to a hash, you need to dereference it with %$ in order to work
with the hash it refers to.

And second, you can get a list of hash keys with the keys (perldoc -f
keys) function:

my @listKeys = keys(%$self->{data}->{list});

sherm--

--
My blog: http://shermspace.blogspot.com
Cocoa programming in Perl: http://camelbones.sourceforge.net

Sherm Pendley wrote:
> Mafj <> writes:
>
>> I have a fixed structure like this (comes from external file):
>>
>> $self->{data} = {
>> 'ver' => 2,
>> 'list' => {
>> 'name1' => 'item1',
>> 'different_name' => 'another_item',
>> 'whatever' => 'special_item',
>> # and 1000 more
>> }
>> };
>> I need a content of $self->{data}->{list}. I do knot know field names
>> nor keys.
>> There is probably some simple loop, foreach or while,e.g.
>> ( ($c,$v) = each %self->{data}->{list} ).
>
> You're pretty close. To begin with, since $self->{data}->{list} is a
> reference to a hash, you need to dereference it with %$ in order to work
> with the hash it refers to.
>
> And second, you can get a list of hash keys with the keys (perldoc -f
> keys) function:
>
> my @listKeys = keys(%$self->{data}->{list});

ITYM: my @listKeys = keys %{$self->{data}->{list}};

$ perl -le'
my $self = { data => { list => { "a" .. "f" } } };
print for keys %$self->{data}->{list};
'
Type of arg 1 to keys must be hash (not hash element) at -e line 3, near
"};"
Execution of -e aborted due to compilation errors.




John
--
Perl isn't a toolbox, but a small machine shop where you
can special-order certain sorts of tools at low cost and
in short order. -- Larry Wall

"John W. Krahn" <> writes:

> Sherm Pendley wrote:
>> Mafj <> writes:
>>
>>> I have a fixed structure like this (comes from external file):
>>>
>>> $self->{data} = {
>>> 'ver' => 2,
>>> 'list' => {
>>> 'name1' => 'item1',
>>> 'different_name' => 'another_item',
>>> 'whatever' => 'special_item',
>>> # and 1000 more
>>> }
>>> };
>>> I need a content of $self->{data}->{list}. I do knot know field names
>>> nor keys.
>>> There is probably some simple loop, foreach or while,e.g.
>>> ( ($c,$v) = each %self->{data}->{list} ).
>>
>> You're pretty close. To begin with, since $self->{data}->{list} is a
>> reference to a hash, you need to dereference it with %$ in order to work
>> with the hash it refers to.
>>
>> And second, you can get a list of hash keys with the keys (perldoc -f
>> keys) function:
>>
>> my @listKeys = keys(%$self->{data}->{list});
>
> ITYM: my @listKeys = keys %{$self->{data}->{list}};

Yep, you're right. That's what I get for banging out code in a post
without testing it.

sherm--

--
My blog: http://shermspace.blogspot.com
Cocoa programming in Perl: http://camelbones.sourceforge.net

Thanks guys the following finally work:

eval `cat ./datafile.pl`;
foreach $x( keys %{$self->{data}->{list} } )
{
print "$x $self->{data}->{list}->{$x}\n";
}
Once again thanks for dropping me line.

Regards,
Maciej