Convert string “a.b.c” to $hash->{a}->{b}->{c} in Perl

问题:

I've dynamic nested hash-refs like this:

my $hash = { 'a' => { 'b' => { 'c' => 'value' } } }; 

I want to set the value of c to 'something' by allowing the user to input "a.b.c something".

Now getting the value could be done like this:

my $keys = 'a.b.c';  my $v='something'; my $h = $hash; foreach my $k(split /\./, $keys) {   $h = $h->{$k}; } print $h; # "value" 

But how would I set the value of key c to $v so that

print Dumper $hash; 

would reflect the change? $h is not a ref at the end of the foreach loop, so changing that won't reflect the change in $hash. Any hints how to solve the knots in my head?

回答1:

Something like this:

my $h = $hash; my @split_key = split /\./, $keys; my $last_key = pop @split_key; foreach my $k (@split_key) {     $h = $h->{$k}; } $h->{$last_key} = $v; 

回答2:

Popping out the last key is for wusses! ;)

sub dive :lvalue {    my $r = \shift;    $r = \( ($$r)->{$_} ) for @_;    return $$r; }  my $data; my $key = 'a.b.c'; my $val = 'value';  dive($data, split /\./, $key) = $val; 

A more powerful (and thus slightly harder to use) version of this function is provided by Data::Diver.

use Data::Diver qw( DiveVal );  my $data; my $key = 'a.b.c'; my $val = 'value';  DiveVal($data //= {}, map \$_, split /\./, $key) = $val; 

(daxim's usage is slightly off.)

回答3:

use strictures; use Data::Diver qw(DiveVal);  my ($hash, $path, $value) = (     { 'a' => { 'b' => { 'c' => 'value' } } },     'a.b.c',     'something', );  DiveVal($hash, split /[.]/, $path) = $value; # { a => { b => { c => 'something' } } } 

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