title: What's the difference between dir() and __dir__?
body: <p>in python what's the difference between <code>dir()</code> function and <code>__dir__</code> attribute in python?</p>
  
  <pre class="lang-none prettyprint-override"><code>&gt;&gt;&gt; 2 .__dir__()
  ['__divmod__', 'real', '__rxor__', '__floor__', '__hash__', '__index__', '__lt__', '__ceil__', '__repr__', '__reduce_ex__', '__rpow__', '__rand__', '__truediv__', '__subclasshook__', '__doc__', '__radd__', '__or__', '__pow__', '__trunc__', '__rrshift__', '__delattr__', '__reduce__', '__rlshift__', 'conjugate', '__xor__', '__rtruediv__', '__rfloordiv__', '__ge__', '__setattr__', '__class__', 'bit_length', '__neg__', '__mod__', '__int__', '__pos__', 'from_bytes', '__format__', '__rmul__', '__lshift__', '__rsub__', '__new__', '__add__', '__floordiv__', 'imag', 'to_bytes', 'numerator', '__dir__', '__abs__', '__init__', '__sizeof__', '__getnewargs__', '__getattribute__', '__invert__', '__gt__', '__rshift__', '__ne__', '__rdivmod__', '__mul__', '__and__', '__sub__', '__rmod__', '__round__', '__ror__', '__le__', '__eq__', '__float__', '__bool__', '__str__', 'denominator']
  &gt;&gt;&gt; dir(2)
  ['__abs__', '__add__', '__and__', '__bool__', '__ceil__', '__class__', '__delattr__', '__dir__', '__divmod__', '__doc__', '__eq__', '__float__', '__floor__', '__floordiv__', '__format__', '__ge__', '__getattribute__', '__getnewargs__', '__gt__', '__hash__', '__index__', '__init__', '__int__', '__invert__', '__le__', '__lshift__', '__lt__', '__mod__', '__mul__', '__ne__', '__neg__', '__new__', '__or__', '__pos__', '__pow__', '__radd__', '__rand__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', '__rfloordiv__', '__rlshift__', '__rmod__', '__rmul__', '__ror__', '__round__', '__rpow__', '__rrshift__', '__rshift__', '__rsub__', '__rtruediv__', '__rxor__', '__setattr__', '__sizeof__', '__str__', '__sub__', '__subclasshook__', '__truediv__', '__trunc__', '__xor__', 'bit_length', 'conjugate', 'denominator', 'from_bytes', 'imag', 'numerator', 'real', 'to_bytes']
  </code></pre>