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memoize() in Groovy

with 5 comments

Memoization generally means remembering the output for the already passed input.

In Groovy, memoization is performed using memoize().

An example of memoize() called on closures is given below,

Example:

def toSquare={a->
  sleep(2000)
  a*a
}.memoize()

//Case 1:
println toSquare(5)           // O/P:25 --> Got after 2000ms
//Case 2:
println toSquare(5)           // O/P:25 --> Got IMMEDIATELY
//Case 3:
println toSquare(6)           // O/P:36 --> Got after 2000ms

In the above code,There is a closure toSquare.

Here any  parameter that is passed into the closure is squared only after 2000ms and above all, the closure is Memoized.

  • Case 1 : When the closure is called for the first time and parameter 5 is passed, the computation is done completely . In accordance with the computational flow, the result is printed only after 2000ms .
  • Case 2: When the closure is called for the second time and the same parameter 5 is passed, computation is not done and the result is displayed immediately. This is becuase of the memoize(). i.e., By Memoization principle , it stores the calculated value of the input that has been passed already.
  • Case 3: Here , a new input is being passed. Computation is done.Result is displayed after 2000ms. However now that , this result for this particular input will be cached.

memoize()                                     –> stores all the new inputs and the corresponding outputs.

memoizeAtLeast(minimum)  –> stores atleast a minimum number of results.

memoizeAtMost(maximum) –> stores the maximum number of results specified .

 

Have a memoizable day 🙂

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Written by thangaveluaishwarya

September 21, 2013 at 11:25 PM