WeakPtr<T extends DartBaseClass>  constructor 
      
      WeakPtr<T extends DartBaseClass> ({ 
    
    
- T? ptr,
Implementation
WeakPtr({T? ptr}) {
  if (ptr is DartBaseProxyClass) {
    this.strongPtr = ptr.weakBaseRC() as T?;
  } else {
    if (ptr != null) {
      this.weakPtr = WeakReference(ptr);
    }
  }
}