Null-coalescing assignment ??= in C#

??= assigns a value only if the left side is null. Introduced in C# 8.

// Before
if (_cache == null)
    _cache = LoadFromDatabase();

// After
_cache ??= LoadFromDatabase();

Useful for lazy initialization. The right side is only evaluated if the left side is actually null — so LoadFromDatabase() doesn’t get called if _cache already has a value.

Works with any nullable reference type or Nullable<T>. Pairs well with ?? for read-only access:

// Return cached value, or load and cache it
return _cache ??= LoadFromDatabase();