younger(fname, varargin)

function res= younger(fname, varargin)
	
% USAGE:    boolean= younger(fname, fname1, fname2, ...)
% 
% Check to see if fname has an older modification date than fname1, fname2, ...
% 
% Returns true if at least one of the files fname1, fname2 etc. has a more recent 
%  modification date than fname. Returns false otherwise. 
% 
% If you find any errors, please let me know! (peder at axensten dot se) 
% 
% fname:    Path (string) to file that might need to be updated. 
% 
% fnameN:   String, or cell array of strings, containing file path(s) to files that fname 
%           depends upon. If any of these has a modification date that is not older than 
%           fname's, then fname needs to be updated. If it is 'checkcallers', the modification 
%           dates of all functions in the calling chain are checked too.
% 
% EXAMPLE:
% if(younger(resultfile, indatafile, which('butchread.m'), 'checkcallers'))
%     result=            do_time_consuming_stuff(indatafile, data);
%     save(resultfile 'result');
% else
%     result=            load(resultfile, 'result');
% end
% 
% NOTE:     If fname (or all fnameN) doesn't exist, younger returns false.
% 
% HISTORY:
% Version 1.0, 2006-04-19.
% Version 1.1, 2006-07-17:
% - Now returns true or false, not a (often empty) list of files.
% Version 1.2, 2006-11-03:
% - Show a much better example.
% Version 1.2, 2007-09-09:
% - A new option, 'checkcallers'. I present, the modification dates of all callers in 
%   the calling chain are checked too.
% 
% Copyright (C) Peder Axensten (peder at axensten dot se), 2006.

% KEYWORDS: update, file date, changed

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	
	% Default values.
	debug=			false;
	res=			false;
	datenumber=		-Inf;
	
	% Check target file.
	if(nargin < 1),				error('There must be at least one argument.');	end
	if(~ischar(fname)), 		error('The first argument must be a string.');	end
	info=			dir(fname);
	if(isempty(info))
		warning('pax:younger:argcheck', 'No such file found: %s', fname);
	end
	if(debug),					disp(info);										end
	if(~isempty(info)), 		datenumber= datenum(info.date);					end
	
	
	% Check the given files.
	N=				0;
	while(N < length(varargin))
		N=				N+1;
		if(ischar(varargin{N}))							% This argument is a string.
			if(strcmp('checkcallers', varargin{N}))			% We're checking the calling functions too.
				thesource=		dbstack('-completenames');	% Get the name of the calling function(s)...
				if(numel(thesource) >= 2)					% ...if there is at least one.
					thesource=	unique({thesource.file});
					varargin=	{varargin{:}, thesource{:}};% Add them to the check list.
				end
			else
				info=			dir(varargin{N});
				if(isempty(info))
					warning('pax:younger:argcheck', 'No such file found: %s', varargin{N});
				else
					if(debug),		disp(info);									end
					res=			(~isempty(info) && (datenumber < datenum(info.date)));
					if(res),		return;			end
				end
			end
		elseif(iscellstr(varargin{N}))					% This argument is a cell-string. 
			varargin=		{varargin{:}, varargin{N}{:}};
		else
			warning('pax:younger:argcheck', ...
				'Only strings or cell strings as arguments! Argument %d is %s.', ...
				N+1, class(varargin{N}));
		end
	end
	
	
end