Add member function to Mesh to read from file

[Prof Garth Wells]

At present, once can only read a mesh from file via the Mesh constructor. This isn't helpful when passing a (shared) pointer to a function that is responsible for initialising a Mesh.

[Anders Logg (Chalmers)]

This should work?

file >> *mesh;

[Prof Garth Wells]

The >> interface is problematic because we can't set options, e.g. pass the MPI communicator.

[Anders Logg (Chalmers)]

OK, question is then whether it should be

mesh.read(filename, options);

or

file.read(mesh, options);

and << can remain as wrappers for read/write functions.

[Prof Garth Wells]

That's at much more general (and important) question with implication across classes!

Given where we've been going with XDMF and HDF5 (where files can have parameters), the latter is probably the most appropriate.

[Martin Sandve Alnæs]

+1 for file.read(mesh, options), allowing e.g. Mesh to be independent of I/O.

[Prof Garth Wells]

Ok, let's move to this across the board. We'll soon add support for ascii XDMF, so for this particular case we'll drop the << syntax.

It will also allow us to make proper use of XML to pull mesh data out explicitly rather than magically behind the scenes.

[Anders Logg (Chalmers)]

OK

[Anders Logg (Chalmers)]

Removing milestone: 1.7 (automated comment)

[Prof Garth Wells]

@chris_richardson Has this been fixed?

[Prof Garth Wells]

@michalhabera @chris_richardson Can this be closed?

[Chris Richardson]

Works for xdmf