Re^4: read flat file and build tree-like structure

Couple of follow-up questions: 1. Could you please explain what the following snippet does?

     my $p = \\%hash;
     $p = \(${$p}->{$_}) for @elts;
     $$p = $val;
[download]

2. Is there a quick/easy way to change the key of a hash? Apologies if I'm breaking a rule here (double/cross-posting)...

Comment on Re^4: read flat file and build tree-like structure Download Code

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Re^5: read flat file and build tree-like structure by ikegami (Patriarch) on Nov 19, 2007 at 19:07 UTC
There's no problem with asking follow up questions. 1. Just like `DiveVal(\%hash, map \$_, @elts) = $val;` [download] it does `$hash{ $elts[0] }{ $elts[1] }...{ $elts[n-1] } = $val;` [download] If you have data like `foo.bar=val foo.bar.baz=val` [download] you'd be better off with pc88mxer's updated code. 2. Keys can be added and removed, not changed. However, combining a removal and an addition is easy. `$hash{$new_key} = delete $hash{$old_key};` [download] or `$hash{$new_key} = delete $hash{$old_key} if exists $hash{$old_key};` [download]	[reply] [d/l] [select]

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There's no problem with asking follow up questions.

1. Just like

DiveVal(\%hash, map \$_, @elts) = $val;
[download]

it does

$hash{ $elts[0] }{ $elts[1] }...{ $elts[n-1] } = $val;
[download]

If you have data like

foo.bar=val
foo.bar.baz=val
[download]

you'd be better off with pc88mxer's updated code.

2. Keys can be added and removed, not changed. However, combining a removal and an addition is easy.

$hash{$new_key} = delete $hash{$old_key};
[download]

$hash{$new_key} = delete $hash{$old_key}
   if exists $hash{$old_key};
[download]