lodash's _.memoize with typescript methods

Question

Does anyone have any experience incorporating lodash's memoize function with a typescript method?

I know typescript supports decorators but I've been having a bit of trouble understanding them.

I created an easy test code to modify with lodash wired to make explaining the solution easier:

https://codepen.io/thinkbonobo/pen/XKyaKY?editors=0010

I'd like to memoize run so that it returns the answer without the forced wait. If it is successfully memoized it will return "MEMOIZED!!! :)"

  run() {
    return this.doSomeProcessing();
  }

(N.B., I would suggest while coding to comment out the wait function so it doesn't give the synchronous lag from it as the program tries to run)

Please include all code necessary to understand the question on Stack Overflow itself, rather than on a third-party site. — Heretic Monkey
– Heretic Monkey, Commented Aug 8, 2016 at 21:59

basarat · Accepted Answer · 2016-08-08 22:00:45Z

2

You can easily memoize run with the once function https://lodash.com/docs#once:

   run = _.once(() => {
     return this.doSomeProcessing();
   });

Of course this makes it a member instead of a method but that's okay🌹.

answered Aug 8, 2016 at 22:00

basarat

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1 Comment

ThinkBonobo Over a year ago

legit! making it an member is a great solution... still I do wish I could have used a decorator to solve this....

fabien0102 · Accepted Answer · 2016-08-30 10:34:18Z

2

A simple and elegant solution for have @memoize() decorator:

function memoize() {
    return function (target: any, functionName: string) {
      target[functionName] = _.memoize(target[functionName]);
    };
}

Live example: http://codepen.io/fabien0102/pen/KgPrOy?editors=0012

answered Aug 30, 2016 at 10:34

fabien0102

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Comments

jsalvata · Accepted Answer · 2018-04-18 10:15:44Z

2

fabien0102's solution can easily be improved to support getters:

export function memoize() {
  return function (target: any, functionName: string, descriptor: PropertyDescriptor) {
    if (descriptor.get) descriptor.get = _.memoize(descriptor.get, function<T>(this: T):T { return this; });
    else descriptor.value= _.memoize(descriptor.value);
  };
}

edited Apr 18, 2018 at 10:15

answered Apr 11, 2018 at 7:16

jsalvata

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