`loadxgendata` cannot handle absolute file paths (with or without `.m`)

[yasirroni]

loadxgendata cannot handle absolute file paths (with or without .m). loadxgendata (via loadgenericdata) cannot accept absolute file paths. It only works with function names that are on the MATLAB/Octave path.

Works (filename on path):

xgd = loadxgendata('ex_xgd_uc', mpc);

FAILS (absolute path with .m):

xgd = loadxgendata('/full/path/to/matpower/most/examples/ex_xgd_uc.m', mpc);
% Error: strips .m, then can't find file

FAILS (absolute path without .m):

xgd = loadxgendata('/full/path/to/matpower/most/examples/ex_xgd_uc', mpc);
% Error: not on MATLAB path

Root Cause:

loadgenericdata.m uses feval(rootname) for .m files, which requires the function to be on MATLAB's path. It doesn't support running .m files from arbitrary absolute paths.

Inconsistency:
loadcase() accepts absolute paths with .m extension, but loadxgendata() does not.

[yasirroni]

Solution, handle with feval_w_path if given input as path.

    elseif strcmp(extension,'.m')       %% from M file
        [pathstr, fname_only, ~] = fileparts(rootname);
        if isempty(pathstr)
            %% no path specified, use feval directly
            if isempty(args)
                var = feval(rootname);
            elseif iscell(args)
                var = feval(rootname, args{:});
            else
                var = feval(rootname, args);
            end
        else
            %% path specified, use feval_w_path
            if isempty(args)
                var = feval_w_path(pathstr, fname_only);
            elseif iscell(args)
                var = feval_w_path(pathstr, fname_only, args{:});
            else
                var = feval_w_path(pathstr, fname_only, args);
            end
        end
    end