copy

Returns this object rebuilt around the replacement geometry polyline — the hook the shape-preserving operations return through.

Every operation that moves a polyline computes its result as a plain Polyline and returns it through this hook. This base implementation returns polyline itself; a subclass overrides it to rebuild an instance of its own class around polyline, and every such operation then comes back as that class. The result's runtime class must equal the receiver's — the operations check it and fail with a named error when a subclass misses the override.

Parameters