clone

Copy a Digest::SHA object, producing an independent duplicate.

Returns a new object with the same algorithm and the same internal state — including any data already absorbed via add or addfile. The copy and the original are independent from that moment on: hashing more data into one does not affect the other.

Useful when you want several digests that share a common prefix, for example hashing a large buffer followed by a per-record suffix.

Synopsis

my $base = Digest::SHA->new(256);
$base->add($prefix);
my $copy = $base->clone;

What you get back

A fresh blessed Digest::SHA object with state copied from the receiver. Returns undef if called on something that is not a valid Digest::SHA object.

Examples

my $base = Digest::SHA->new(256);
$base->add("common-prefix:");
for my $id (1 .. 3) {
    my $h = $base->clone;
    $h->add($id);
    print $h->hexdigest, "\n";   # three distinct digests
}

my $sha = Digest::SHA->new(512);
$sha->add("abc");
my $copy = $sha->clone;
print $copy->hexdigest eq $sha->hexdigest ? "same\n" : "diff\n"; # same

Edge cases

• The copy is a snapshot: subsequent add on the receiver does not propagate into it.

• clone on a non-Digest::SHA scalar returns undef rather than croaking.

Differences from upstream

Fully compatible with upstream Digest::SHA 6.04.

See also

• new — start a fresh context instead of branching from an existing one.

• reset — reuse the same object for the next digest.

• getstate / putstate — snapshot to a string you can send across processes.