A proxy is useful in several circumstances, for example, consider the following ones: Data validation: The proxy validates the input before forwarding it to the subject Security: The proxy verifies that the client is authorized to perform the operation and it passes the request to the subject only if the outcome of the check is positive Caching: The proxy keeps an internal cache so that the operations are executed on the subject only if the data is not yet present in the cache Lazy initialization: If the creation of the subject is expensive, the proxy can delay it to when it's really necessary
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