| Re: [eigen] Feature request - Prevent dynamic resizing of a matrix |
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- To: eigen@xxxxxxxxxxxxxxxxxxx
- Subject: Re: [eigen] Feature request - Prevent dynamic resizing of a matrix
- From: Benoit Jacob <jacob.benoit.1@xxxxxxxxx>
- Date: Wed, 28 Jan 2009 17:45:49 +0100
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It's added in trunk now (won't make it into 2.0).
Commit msg:
add EIGEN_NO_AUTOMATIC_RESIZING
if defined, already initialized matrices won't be automatically
resized in assignments
uninitialized matrices may still be initialized
Cheers,
Benoit
2009/1/28 Benoit Jacob <jacob.benoit.1@xxxxxxxxx>:
> 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...
>
> Cheers,
> Benoit
>
> 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
>>
>>
>>
>