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MediumPro challengeJavaScriptTypeScript

Decorator Pattern in TypeScript

TypeScriptPatternsDesign

TypeScript decorators are functions that wrap and augment classes, methods, or properties:

function Log(target: unknown, key: string, descriptor: PropertyDescriptor) {
  const original = descriptor.value;
  descriptor.value = function (...args: unknown[]) {
    console.log(`[${key}] called with`, args);
    return original.apply(this, args);
  };
  return descriptor;
}

class UserService {
  @Log
  getUser(id: string) { /* ... */ }
}

The same pattern works as plain higher-order functions — which is the approach here (Judge0 doesn't need the @ syntax).

Your Task

Implement three method-wrapping utilities:

UtilityBehaviour
memoizeMethod(fn)Cache results by stringified args — same args → same result, no re-execution
logMethod(fn, name)Push "[name] called with [args]" to callLog before each call
retryMethod(fn, n)Retry up to n times on error before re-throwing

Sample tests

Test #1memoize: fn called only once for same args
Input: ["memoize",5]
Output: 1
Test #2log decorator formats correctly
Input: ["log","fetchUser",42]
Output: "[fetchUser] called with [42]"
Test #3retry succeeds on 2nd attempt with 3 retries allowed
Input: ["retry",3,2]
Output: "ok"
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