Re^4: How come undef eq '' ??

in reply to Re^3: How come undef eq '' ??
in thread How come undef eq '' ??

This code feels... itchy... to me. No offense ;)

Let's assume ref($hash) ne 'HASH', then $data = $hash, so ref($data) will never eq 'HASH', so that statement modifier on the last line is redundant in this case.

However, say ref($hash) eq 'HASH' is true, then $data = $$hash{$name}, and then $data = $$data{CONTENT} provided that $$hash{$name} is a hashref. For the sake of argument, let's say it isn't. Then $data will still be $$hash{$name}. Is that how it's supposed to work?

Comment on Re^4: How come undef eq '' ?? Select or Download Code

Replies are listed 'Best First'.
Re^5: How come undef eq '' ?? by tmharish (Friar) on Jan 31, 2013 at 07:05 UTC
This code feels... itchy... to me. No offense ;) None Taken! The idea of this bit is to extract the next level of an XML tree ( stored in a hash, in this case `$hash` ) So if `ref( $hash ) ne 'HASH'` then we are at a leaf and $hash is the actual value and not a sub-tree, and hence the `$data = $hash` ( now they are both scalar ) On the other hand, if `ref($hash) eq 'HASH'` then we are dealing with a sub-tree - so `$data = $$hash{$name}` is fine. There is, however, one exception, and that is when `'$hash'` contains the key `'CONTENT'` like so: `$$hash{ CONTENT }`. In that case `$$hash{ CONTENT }` is not a sub-tree but a place holder for the actual data and hence the `$data = $$data{CONTENT}` Of course this requires that `CONTENT` is never a key in our hash (although it might be a node in the XML) - but that is achieved during parsing of the XML into the hash.	[reply] [d/l] [select]

Replies are listed 'Best First'.

Re^5: How come undef eq '' ??
by tmharish (Friar) on Jan 31, 2013 at 07:05 UTC

This code feels... itchy... to me. No offense ;)

None Taken!

The idea of this bit is to extract the next level of an XML tree ( stored in a hash, in this case $hash )

So if ref( $hash ) ne 'HASH' then we are at a leaf and $hash is the actual value and not a sub-tree, and hence the $data = $hash ( now they are both scalar )

On the other hand, if ref($hash) eq 'HASH' then we are dealing with a sub-tree - so $data = $$hash{$name} is fine.

There is, however, one exception, and that is when '$hash' contains the key 'CONTENT' like so: $$hash{ CONTENT }. In that case $$hash{ CONTENT } is not a sub-tree but a place holder for the actual data and hence the $data = $$data{CONTENT}

Of course this requires that CONTENT is never a key in our hash (although it might be a node in the XML) - but that is achieved during parsing of the XML into the hash.

[reply]
[d/l]
[select]

In Section Seekers of Perl Wisdom