Re: [Boost-users] [exception] array tags

On Sat, Oct 24, 2009 at 8:09 PM, Diederick C. Niehorster wrote:

Hi,

I have just discovered boost::exception and am very happy I did. One thing i would like to do, but haven't yet figure out:

I have a matrix class for which I want to throw exceptions when out_of_range requests are made. One of the extra tags I want to attach is the dimensions of the matrix and it would be neat if i can put those in an array. Defining the tag is no problem, getting the info in there is:

defining: typedef boost::error_info std_range_size;

I have tried: << std_range_size({m_nRows, m_nCols}); size_t a[2] = {m_nRows, m_nCols}; << std_range_size(a); and desperately even << std_range_size() = {m_nRows, m_nCols}; which doesn't make much sense

Option 1, you can use boost::tuple with two separate tags: #include typedef boost::error_info std_range_rows; typedef boost::error_info std_range_cols; typedef boost::tuple std_range_size; With this in place you can throw whatever() << std_range_size(m_nRows,m_nCols); The above still adds two individual error infos: at the catch site you'd still need separate get_error_info calls to get the rows and the cols. Option 2, you can put rows and cols in a struct and make that your error_info type: struct rc { size_t rows, cols; rc( size_t r, size_t c ): rows(r), cols(c) { } }; typedef boost::error_info std_range_size; and then throw whatever() << std_range_size(m_nRows,m_nCols); Emil Dotchevski Reverge Studios, Inc. http://www.revergestudios.com/reblog/index.php?n=ReCode