On 9 Feb., 05:22, "Aaron S. Meurer" <[email protected]> wrote:
> I am trying to create a branch that backports all of my non-Risch Algorithm
> commits from my integration3 branch. One
> commit,https://github.com/asmeurer/sympy/commit/846af4a187800a97520d771dc9e1...,
> which is related tohttp://code.google.com/p/sympy/issues/detail?id=1991,
> changes the exceptions in the code of matrices.py a little bit. I am not so
> sure now what the best way to have things is, though.
>
> Currently, there is a MatrixError exception, which is only used in one place
> in matrices.py, and there I believe ShapeError should be used instead. All
> over the code there is "assert self.cols == self.rows". I have replaced all
> of these with NonSquareMatrixError, which I for some reason have renamed
> NonSquareMatrixException to. So my questions are:
>
> 1. Should we have MatrixError, and if so, how should it be structured?
>
> 2. Should it be called NonSquareMatrixError or NonSquareMatrixException? It
> is raised in those cases where only a square matrix makes sense but a
> non-square matrix was given (like Matrix.det()).
>
> The current structure of the exceptions is
>
> class NonSquareMatrixException(Exception):
> pass
>
> class ShapeError(ValueError):
> """Wrong matrix shape"""
> pass
>
> class MatrixError(Exception):
> pass
>
> but I think it should be more like
>
> class MatrixError(Exception):
> """
> If this is never raised directly, is it needed?
> """
> pass
>
> class ShapeError(ValueError, MatrixError):
> """Wrong matrix shape"""
> pass
>
> class NonSquareMatrixException(ShapeError):
> pass
I would drop NonSquareMatrixException() completely, in my opinion this
is overkill. Maybe just replace it with something like
raise ShapeError('square matrix expected, got %i x %i matrix')
MatrixError() makes sense when you want to catch matrix-related errors
only and ShapeError() is to specific.
But I wonder, in which case a "MatrixError" is not a "ShapeError"? If
there is none, MatrixError should be dropped too.
Vinzent
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