At 01:00 AM 6/18/01 -0500, Teresa Raymond wrote:
>I'm sorry, but I mean could you explain the syntax of the whole line.
Always ask the list, not an individual respondent. I may be gone for a
month in Antarctica or something.
>>At 10:08 PM 6/17/01 -0500, you wrote:
>>>Could you please explain this syntax? Why does people not have a $ sign?
>>
>>Because it didn't in the code you posted. I was following your syntax,
>>which made 'people' a literal key.
>>
>>>> foreach my $person (@{$state{$city}{$street}{people}}) {
Okay, here's a syntax-reading explanation:
foreach my $person (@{$state{$city}{$street}{people}})
reads as
foreach my $person (LIST)
i.e., set a lexical variable $person to each member of LIST in turn for the
duration of a block to follow. The scope of $person will be that
block. Now, what is LIST?
@{$state{$city}{$street}{people}}
reads as
@{something returning reference to ARRAY}
What returns the arrayref?
$state{$city}{$street}{people}
Which can be written (using the knowledge that arrows are implied between
adjacent curlies and square brackets) as
$state{$city}->{$street}->{people}
Because the arrows are evaluated left-to-right, we dissect them
right-to-left, hence
Something returning hashref->{people}
We are getting the element whose key is 'people' from a hash referenced by
something. By what?
$state{$city}->{$street}
Which by the same token is:
Something returning hashref->{$street}
We are getting the element whose key is $street from a hash referenced by
something. By what?
$state{$city}
That is the element whose key is $city from the hash %state. Now we can
put it all together:
foreach my $person (@{$state{$city}{$street}{people}}) means:
Set the lexical $person in turn to each of the members of the array
referenced by the element with key 'people' in the hash referenced by the
element with key $street in the hash referenced by the element $city in the
hash %state.
--
Peter Scott
Pacific Systems Design Technologies
http://www.perldebugged.com
