Re: [eigen] Feature request - Prevent dynamic resizing of a matrix

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OK, this has been a tough decision. Let's recall the arguments on both sides.
In favor of automatic resizing:
1) This is more practical for the majority
2) This is the usual behavior of objects in C++ and in the C++ STL
3) Because this is what STL containers assume, it's almost required in
order to allow convenient usage of STL containers with Eigen types
Against automatic resizing:
1) Exactly what you say. Indeed automatic resizing can hide nasty bugs.

So the default behavior will stay as it is right now, but what you
propose, with a #define, sounds like a good solution to me. I
implement it now. I'd rather call it EIGEN_NO_AUTOMATIC_RESIZING
because i think we still want to allow explicitly calling resize().

Notice that one could also consider implementing this behavior as a
matrix type option. So you would do
typedef Eigen::Matrix<float, Eigen::Dynamic, Eigen::Dynamic,
Eigen::NonResizable> MyMat;
and then objects of type MyMat have this behavior. Stuff to consider for 2.1...


2009/1/28 Timothy Hunter <tjhunter@xxxxxxxxxxxx>:
> Hello all,
> I has been decided that the operator=(A,B) would resize A if it does
> not fit the size of B, right?
> I had a bug in my code I had problems to detect because of this
> feature. It would be nice to have an assert that fails if the matrices
> are of different size, and let the user decide to use this assert with
> some flag definitions like EIGEN_DO_NOT_RESIZE_DYNAMIC_MATRICES.
> Is it possible to do it with the current code?
> -- Timothy Hunter

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