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Like Memoize, but designed for mutable and parametizable objects Use when: 1. You have one expensive method (\compute) which set many internal variables. So, is preferable lazy evaluation of these dependent variables. 2. The expensive operation depends on one or more parameters 3. Changes on one or more parameters affect all dependent variables 4. You may want to hide the call of 'compute' operation 5. The user could want test several different parameters values