Containers should allow module assignments

[pytorch]

Containers should allow module assignments

[colesbury]

We may want to prefer this syntax (in examples and docs) instead of the current keyword arguments in the constructor.

For example:

class MyNetwork(nn.Container):
  def __init__(self):
    super(nn.Container, self).__init__()
    self.l1 = nn.Linear(5, 10)
    self.l2 = nn.Linear(10, 20)

instead of:

class MyNetwork(nn.Container):
  def __init__(self):
    super(nn.Container, self).__init__(
      l1=nn.Linear(5, 10),
      l2=nn.Linear(10, 20),
    )

One advantage is that the order of module iteration would match the order of assignment, which is not true for the constructor syntax (except in the upcoming Python 3.6)

[apaszke]

@colesbury good point. We should probably do the same for parameters