getargs.m

function [eid,emsg,varargout]=getargs(pnames,dflts,varargin)
%GETARGS Process parameter name/value pairs 
%   [EID,EMSG,A,B,...]=GETARGS(PNAMES,DFLTS,'NAME1',VAL1,'NAME2',VAL2,...)
%   accepts a cell array PNAMES of valid parameter names, a cell array
%   DFLTS of default values for the parameters named in PNAMES, and
%   additional parameter name/value pairs.  Returns parameter values A,B,...
%   in the same order as the names in PNAMES.  Outputs corresponding to
%   entries in PNAMES that are not specified in the name/value pairs are
%   set to the corresponding value from DFLTS.  If nargout is equal to
%   length(PNAMES)+1, then unrecognized name/value pairs are an error.  If
%   nargout is equal to length(PNAMES)+2, then all unrecognized name/value
%   pairs are returned in a single cell array following any other outputs.
%
%   EID and EMSG are empty if the arguments are valid.  If an error occurs,
%   EMSG is the text of an error message and EID is the final component
%   of an error message id.  GETARGS does not actually throw any errors,
%   but rather returns EID and EMSG so that the caller may throw the error.
%   Outputs will be partially processed after an error occurs.
%
%   This utility can be used for processing name/value pair arguments.
%
%   Example:
%       pnames = {'color' 'linestyle', 'linewidth'}
%       dflts  = {    'r'         '_'          '1'}
%       varargin = {{'linew' 2 'nonesuch' [1 2 3] 'linestyle' ':'}
%       [eid,emsg,c,ls,lw] = statgetargs(pnames,dflts,varargin{:})    % error
%       [eid,emsg,c,ls,lw,ur] = statgetargs(pnames,dflts,varargin{:}) % ok

% We always create (nparams+2) outputs:
%    one each for emsg and eid
%    nparams varargs for values corresponding to names in pnames
% If they ask for one more (nargout == nparams+3), it's for unrecognized
% names/values

%   Original Copyright 1993-2008 The MathWorks, Inc. 
%   Modified by Deng Cai (dengcai@gmail.com) 2011.11.27




% Initialize some variables
emsg = '';
eid = '';
nparams = length(pnames);
varargout = dflts;
unrecog = {};
nargs = length(varargin);

% Must have name/value pairs
if mod(nargs,2)~=0
    eid = 'WrongNumberArgs';
    emsg = 'Wrong number of arguments.';
else
    % Process name/value pairs
    for j=1:2:nargs
        pname = varargin{j};
        if ~ischar(pname)
            eid = 'BadParamName';
            emsg = 'Parameter name must be text.';
            break;
        end
        i = strcmpi(pname,pnames);
        i = find(i);
        if isempty(i)
            % if they've asked to get back unrecognized names/values, add this
            % one to the list
            if nargout > nparams+2
                unrecog((end+1):(end+2)) = {varargin{j} varargin{j+1}};
                % otherwise, it's an error
            else
                eid = 'BadParamName';
                emsg = sprintf('Invalid parameter name:  %s.',pname);
                break;
            end
        elseif length(i)>1
            eid = 'BadParamName';
            emsg = sprintf('Ambiguous parameter name:  %s.',pname);
            break;
        else
            varargout{i} = varargin{j+1};
        end
    end
end

varargout{nparams+1} = unrecog;