my %$foo=("key1"=>"value1","key2"=>"value2");

I think you really want:

my %foo=("key1"=>...);
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The difference is that $foo refers to the scalar variable whereas $foo{'key1'} accesses the hash %foo (with key key1).

If you want to create a reference to a hash, use curly braces:

my $hash_ref = { key1 => ... };
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and then you access values in the hash with the -> operator, e.g. $hash_ref->{key1}.