Add shortcut to find out if an AbstractArray is differentiable

[HGSilveri]

• Adds AbstractArray.is_differentiable, which checks if the stored array is a tensor with requires_grad=True

[a-corni]

It really looks good to me, but I would really much prefer having this property be named requires_grad, because that's how we use it in all our tests. However, if having is_differentiable is needed to improve the user experience, I suggest we have two properties requires_grad and is_differentiable, with is_differentiable simply returning requires_grad.

[HGSilveri]

It really looks good to me, but I would really much prefer having this property be named requires_grad, because that's how we use it in all our tests. However, if having is_differentiable is needed to improve the user experience, I suggest we have two properties requires_grad and is_differentiable, with is_differentiable simply returning requires_grad.

Our tests were written with requires_grad because we were accessing the torch tensor directly. I don't think they should have a big influence on this naming decision.
That being said, I'm not strongly opinionated on this and I'm willing to change the name. I'm just puzzled as to what cases you feel that requires_grad covers and is_differentiable doesn't.

[a-corni]

It really looks good to me, but I would really much prefer having this property be named requires_grad, because that's how we use it in all our tests. However, if having is_differentiable is needed to improve the user experience, I suggest we have two properties requires_grad and is_differentiable, with is_differentiable simply returning requires_grad.

Our tests were written with requires_grad because we were accessing the torch tensor directly. I don't think they should have a big influence on this naming decision. That being said, I'm not strongly opinionated on this and I'm willing to change the name. I'm just puzzled as to what cases you feel that requires_grad covers and is_differentiable doesn't.

As I said above, I think we can have two properties. I am just saying that having a property requires_grad could be useful, but since the issue is the user-friendliness, then adding is_differentiable as well would make sense

[a-corni]

LGTM ! Thanks :)