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:
sub dive_val :lvalue {
my $p = \shift;
$p = \( ($$p)->{$_} ) for @_;
return $$p;
}
my $data;
my $key = 'a.b.c';
my $val = 'value';
dive_val($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' } } }
来源:https://stackoverflow.com/questions/10965006/convert-string-a-b-c-to-hash-a-b-c-in-perl