Incubator-mxnet: [Feature Request] consistent behavior of reshape() in ndarray and symbol mode

[chongruo]

For reshape() operator, I found that it works with input which is not a tuple. For example:

x = mx.nd.array([1,2,3,4])

y = x.reshape(2,2)   # input is not a tuple
# y = [[1. 2.]
#     [3. 4.]]

y = x.reshape((2,2))    
# y = [[1. 2.]
#     [3. 4.]]

However, the bebavior is not consistent in symbol mode for reshape() with non-tuple input. It will raise an error.

It is bothering that when implementing hybrid_forward() in HybridBlock, codes( F.reshape() ) in two modes are the same. We usually disable hybridized mode for debugging (printing shape, context), and then enable it for efficiency. Since error messages in hybridized mode are a little vague, this inconsistent behavior of reshape() makes users hard to realize the reason of the error, and also hard to debug.

[mxnet-label-bot]

Hey, this is the MXNet Label Bot.
Thank you for submitting the issue! I will try and suggest some labels so that the appropriate MXNet community members can help resolve it.
Here are my recommended label(s): Feature

[leezu]

Hi @chongruo, I'm preparing a RFC to unify symbolic and imperative interfaces and handle the difference in the backend automatically. I'll comment here once the RFC is published. It would resolve this feature request.