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Objects Own Resources (RAII)


Make sure that objects own resources. This principle is also known as “resource acquisition is initialization” or “RAII.”

Pass every “new” object as a constructor argument to another named object that owns it (almost always unique_ptr).

void f() {
  unique_ptr<widget> p( new widget(…) );
  my_class x( new widget() );
} // automatic destruction and deallocation for both widget objects
  // automatic exception safety, as if “finally { p->dispose(); x.w.dispose(); }”

Always immediately pass any new resource to another object that owns it.

void g() {
  other_class y( OpenFile() );
} // automatic closing and release for file resource
  // automatic exception safety, as if “finally { y.file.dispose(); }”

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