Allow the reordering of a DiscreteDomain

[EmilyBourne]

Add a function to initialise a DiscreteDomain from a DiscreteDomain with a different ordering. Fixes #419

[tpadioleau]

I think it should already be addressed by existing constructors. Can you provide an example that does not compile ?

[EmilyBourne]

I think it should already be addressed by existing constructors. Can you provide an example that does not compile ?

Hmm, it seems that you are right. The tests I have added already work on the main branch. The assignment operator doesn't work:

DDomZYX const dom_z_y_x = dom_x_y_z;

but maybe this is intentional?

[tpadioleau]

I think it should already be addressed by existing constructors. Can you provide an example that does not compile ?

Hmm, it seems that you are right. The tests I have added already work on the main branch. The assignment operator doesn't work:

DDomZYX const dom_z_y_x = dom_x_y_z;

but maybe this is intentional?

I see, I do not see a good reason to not support this assignment operator, it seems to be an equivalent of the reordering & slicing constructor.

[tpadioleau]

Actually this syntax is not related to the assignment operator. It only involves either the constructor or a cast operator.

That being said, I think it is worth having an equivalent assignement operator of the slicing and reordering constructor.

[tpadioleau]

Thanks, do we really need both the 2D and 3D versions then ?

[EmilyBourne]

Thanks, do we really need both the 2D and 3D versions then ?

I don't think so, 3D should be sufficient. I will remove the 2D version