title: Pytorch What's the difference between define layer in __init__() and directly use in forward()?
body: <p>What is the difference between the method that define layers in <code>__init__()</code> function, call layer in forward later and the method that directly use layer in <code>forward()</code> function ?<br>
  Should I define every layer in my compute graph in constructed function(eg. <code>__init__</code>) before I write my compute graph?<br>
  Could I direct define and use them in <code>forward()</code>? </p>