Test for array or hash - ok, but what to do about it?

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

Hi PMs
I'm processing XML (using XML::Simple) and find that one of the fields I process is sometimes duplicated and thus shows up as an array - sometimes...

I have solved it with the following snippet:-


if(ref($content->{'A'}) eq 'ARRAY'){
  # this is an array so need the [0] in there
  $x=$content->{'A'}[0]{'R1'}{'T1'}{'S1'},
  $y=$content->{'A'}[0]{'R1'}{'T1'}{'content'}
  .
  . # more dereferencing further along the tree
}else{
  # this is not an array 
  $x=$content->{'A'}{'R1'}{'T1'}{'S1'},
  $y=$content->{'A'}{'R1'}{'T1'}{'content'}
  .
  . # more dereferening further along the tree
}
[download]

However - this duplicates the great big chunks of dereferencing code... When there are duplicates, I only need the first one so only need branches under $content->{'A'}[0]{etc}...

How to make it simpler without repeating code?
I tried using a string variable in place of the {A}[0] - something like :-

$ifarray = "{'A'}[0]" else $ifarray = "{'A'}"
[download]

but that didn't work.
Suggestions, comments and solutions welcome!
Thanks in advance.
z

Comment on Test for array or hash - ok, but what to do about it? Select or Download Code

Replies are listed 'Best First'.
Re: Test for array or hash - ok, but what to do about it? by Fletch (Bishop) on May 17, 2009 at 16:16 UTC
`my $content_handle = ( ref( $content->{'A'} ) eq 'ARRAY' ) ? $content->{'A'}->[0] : $content->{'A'};` The cake is a lie. The cake is a lie. The cake is a lie.	[reply] [d/l]
Re: Test for array or hash - ok, but what to do about it? by Anonymous Monk on May 17, 2009 at 16:07 UTC
use option `ForceArray=>1` that ways you always use `->{A}[0]`	[reply] [d/l] [select]
Re^2: Test for array or hash - ok, but what to do about it? by Jenda (Abbot) on May 17, 2009 at 21:46 UTC
That would force you to handle all tags as arrays, including those that are never repeated. It's better to specify what tags can be repeated in `ForceArray => [qw(A B D)]`. Or use XML::Rules that gives you even more detailed control. Jenda Enoch was right! Enjoy the last years of Rome.	[reply] [d/l]
Re: Test for array or hash - ok, but what to do about it? by zerocred (Beadle) on May 17, 2009 at 16:39 UTC
great stuff - both great ideas! Thanks guys.... z	[reply]