[Octave-bug-tracker] [bug #33216] cell2struct does not allow to create an empty struct

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?33216>

                 Summary: cell2struct does not allow to create an empty struct
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Tue 03 May 2011 01:43:24 PM UTC
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Improvement/Optimization
                  Status: None
             Assigned to: None
         Originator Name: Jochen Weber
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 3.4.0
        Operating System: Mac OS

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Details:

In many of my codefiles I'm currently using the following syntax to produce a
0x0 struct with a fix set of fields (against which I later run checks) but no
content (no memory required for pointers, etc.):


init_struct = cell2struct(cell(0, 0, 2), {'field1', 'field2'}, 3);


In Matlab this works as expected:

 - taking the dims of the first input that are not the fieldnames dim (0 and
0) as output dims
 - and then creating the output struct with the requested fields

As a workaround I'm currently using a function to initialize structs:


function s = emptystruct(fields, dim)

% argument check
if nargin < 1 || ...
   ~iscell(fields)
    error( ...
        'neuroelf:BadArgument', ...
        'Bad or missing argument.' ...
    );
end
if nargin < 2 || ...
   ~isa(dim, 'double') || ...
    numel(dim) < 2 || ...
    numel(dim) ~= size(dim, 2) || ...
    any(isinf(dim) | isnan(dim) | dim < 0 | dim >= 2^31 | dim ~= fix(dim))
    dim = [0, 0];
end
dim0 = (prod(dim) == 0);

% create struct
if numel(fields) == 0;
    s = struct;
else
    s = cell2struct(cell(numel(fields), 1), fields(:)', 1);
end
if dim0
    s(:) = [];
    if any(dim > 0)
        s = reshape(s, dim);
    end
else
    s = repmat(s, dim);
end






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