create Vector from temporary VectorView fails

[Peter]

This code does not compile

	utility::Matrix m(10,3);
	utility::Vector v2(m.row_view(1));

[Peter]

Hm, this is a documented weakness. Use

utility::Matrix m(10,3);
utility::Vector v2(m.row_view(1));

to achieve the desired result.

[Peter]

I meant

utility::Matrix m(10,3);
utility::Vector v2(m.row_const_view(1));

[Peter]

Similarily:

Matrix result(10,10, 0.0);
Matrix m(10,10, 1.0);
utility::VectorView vv=result.column_view(2);
vv=m.column_view(3); 

does not compile. Likewise to mentioned above a workaround would be

Matrix result(10,10, 0.0);
Matrix m(10,10, 1.0);
utility::VectorView vv=result.column_view(2);
vv=m.column_const_view(3); 

This ticket should not be closed though because it is a severe weakness.

[Peter]

This problem could be avoided with the new rvalue semantics that will be included in the C++0x standard as described ​here.

This feature is included in ​gcc 4.3, so one could solve this for users using gcc 4.3 or later, but since I'm sitting with 4.1 I won't be able to implement that in the near future. Also, I'm not sure it's wise to fork the library like that.

[Peter]

This article seems useful

​http://www.nd.edu/~ahenrick/auto_ptr.pdf

[Peter]

(In [1720]) adding some tests that refs #474. The commented code should compile before closing this ticket

[Peter]

Having this working, we should perhaps add implicit conversion from VectorView? to VectorConstView? (as discussed in #467).

[Peter]

​Boost.Move provides macros to write move construction/assignment for both c++03 and c++11 compilers.

[Peter]

I suggest we implement move construction/assignment for at least Matrix and Vector classes.

[Peter]

Boost.Move was introduced in boost-1.48 which was released 2011-11-15. I'm reluctant to introducing a dependency to such as recent version. Both RHEL6 and CentOS6, for example, distribute Boost-1.41.

[Peter]

It struck me that we could implement this conditionally i.e. only implement if boost 1.48 (or newer) is available. One could also implement if compiler is modern enough. Or combine these option in:

#if this
do this
#elif that
do that
#else
do nothing
#endif

Not sure in which order to pick things, but my gut feeling is that one should implement clean without boost if compiler supports it, otherwise use boost if boost is available, else skip. Note, that boost itself does some selection based on used compiler.

[Peter]

It is perhaps time to upgrade required boost version, so we can look at this.

[Peter]

(In [3587]) move constructor for vector; refs #878 and #474

[Peter]

Test code added in r1720 compiles with GCC 4.8.5 in c++98 mode.

[Peter]

(In [3594]) uncomment test code that used to be problematic. refs #474

[Peter]

(In [3595]) implicit conversion from VectorView? to VectorConstView?. closes #474