Apex Lazy Load Constants

Photo by AbsolutVision on Unsplash

Just a quick note to talk about a pattern to lazy load constants (similar to an old question in Stackoverflow).

Problem

Sometimes you have a class full of constants and some of those are resource intensive (CPU or memory).

Solution

Lazy load those constants:

public static final Map<String, String> ISO_TO_SYMBOL {
  get {
   if (ISO_TO_SYMBOL == null) {
    ISO_TO_SYMBOL = new Map<String, String>{
     'USD' => '$',
     'CAD' => '$',
     'EUR' => '€',
     'GBP' => '£',
     'JPY' => '¥',
     'KRW' => '₩',
     'CNY' => '元'
    };
   }
   return ISO_TO_SYMBOL;
  }
  set;
 }

Benefits

1. Assure the static instance is never changed: constant.
2. Load the map only if requested: lazy load.

Drawback

1. More convoluted code.

Question

Is this a supported pattern or just a corner case? Asking because have not found an example online.