function ft_preamble(cmd, varargin)

% FT_PREAMBLE is a helper function that is included in many of the FieldTrip

% functions and which takes care of some general settings and operations at the

% begin of the function.

%

% This ft_preamble m-file is a function, but internally it executes a

% number of private scripts in the callers workspace. This allows the

% private script to access the variables in the callers workspace and

% behave as if the script were included as a header file in C-code.

%

% See also FT_POSTAMBLE

% Copyright (C) 2011-2012, Robert Oostenveld, DCCN

%

% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org

% for the documentation and details.

%

% FieldTrip is free software: you can redistribute it and/or modify

% it under the terms of the GNU General Public License as published by

% the Free Software Foundation, either version 3 of the License, or

% (at your option) any later version.

%

% FieldTrip is distributed in the hope that it will be useful,

% but WITHOUT ANY WARRANTY; without even the implied warranty of

% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

% GNU General Public License for more details.

%

% You should have received a copy of the GNU General Public License

% along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.

%

% $Id$

% ideally this would be a script, because the local variables would then be

% shared with the calling function. Instead, this is a function which then

% passes the variables explicitly to another script which is eval'ed.

% the following section ensures that these scripts are included as

% dependencies when using the MATLAB compiler

%

%#function ft_preamble_init

%#function ft_preamble_debug

%#function ft_preamble_provenance

%#function ft_preamble_loadvar

%#function ft_preamble_randomseed

% this is a trick to pass the input arguments into the ft_preamble_xxx script

assignin('caller', 'preamble_argin', varargin);

full_cmd = ['ft_preamble_' cmd];

cmd_exists = false;

if exist(full_cmd, 'file')

% Matlab can find commands in a private subdirectory; Octave cannot.

% If pwd is already the private directory, or if using Matlab then

% the command can be evaluated directly

cmd_exists = true;

elseif ~ft_platform_supports('exists-in-private-directory')

% Octave does not find files by name in a private directory, so the full

% filename must be specified.

private_dir=fullfile(fileparts(which(mfilename)),'private');

full_path=fullfile(private_dir,[full_cmd '.m']);

cmd_exists=exist(full_path,'file');

full_cmd_parts = {'ft_tmp_orig_pwd=pwd();',...

'ft_tmp_orig_pwd_cleaner='...

'onCleanup(@()cd(ft_tmp_orig_pwd));',...

sprintf('cd(''%s'');',private_dir),...

[full_cmd ';'],...

'clear ft_tmp_orig_pwd_cleaner;'};

full_cmd = sprintf('%s',full_cmd_parts{:});

end

if ~cmd_exists

% XXX earlier versions would not do anything if ~cmd_exists,

% but fail silently (without raising an error or warning).

% Should that behavior be kept?

ft_error('Could not run %s - does not seem to exist', full_cmd);

end

evalin('caller', full_cmd);