#18529: Topological manifolds: basics
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Reporter: egourgoulhon | Owner: egourgoulhon
Type: enhancement | Status: needs_info
Priority: major | Milestone: sage-6.10
Component: geometry | Resolution:
Keywords: topological | Merged in:
manifolds | Reviewers: Travis Scrimshaw
Authors: Eric Gourgoulhon | Work issues:
Report Upstream: N/A | Commit:
Branch: | 0fb39df7fafe7f0a765bf73b3f34a6cb41e65c40
u/tscrim/top_manifolds_refactor | Stopgaps:
Dependencies: #18175 |
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Comment (by egourgoulhon):
Replying to [comment:69 tscrim]:
> I wasn't imagining that they would be singletons,
OK (I thought that since you were using singletons for the topological
structure, you planed to use them for any kind of structure).
> as they would carry instance information like differential order.
Regarding the specific case of the differential order, we may also
consider that it is part of the structure per se and not of the instance,
i.e. consider that a C^2^-structure differs from a C^4^-structure.
> > Then, how could one have a single class for all kind of manifolds? For
instance, the class `DifferentiableManifold` introduced in #18783 inherits
from `TopologicalManifold` and has the additional attributes `_frames`,
`_coframes`, `_frame_changes`, `_parallelizable_parts`,
`_vector_field_modules`, etc., which have no meaning for a topological
manifold. Besides, we don't want the user to write something like `v =
M.structure().vector_frame(...)` instead of `v = M.vector_frame(...)`, do
we?
>
> Good point. Then rather these being instance objects, they should
probably be mix-in classes. This would help keep some separation of
concerns, avoid some redundancies, and make it easy to manage the
distinction between the full manifold and the submanifolds.
Could you please describe further how you would use mix-in classes? and
why this would be superior to the simple heritage `TopologicalManifold <--
DifferentiableManifold` ?
--
Ticket URL: <http://trac.sagemath.org/ticket/18529#comment:70>
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