Matlab - Do action after every line - matlab

Question

Is there an elegant way to tell matlab to perform a predefined action after the execution of every line in a certain script? By elegant I mean no calling of the action after every line, but rather something like a simple command given at the start of the script.
Example:
Action --> disp('Performing Action');
script:
a = 1;
b = 2;
c = 3;
So the desirable outcome is that after each assignment (of a, b and c), the disp() command would be performed.

Answer 1

You can automatically create a modifed file that has the desired action included at the end of each line:
action = 'disp(''Performing Action'');'; %// action to be added at the end of each line
file = 'script.m'; %// original script
file_out = 'script_out.m'; %// modified script with action added
x = importdata(file); %// cell array of strings. Each line of the
%// original file is a string
x = strcat(x, {' ; '}, action); %// add action at the end of each string,
%// preceded with `;` in case the original line
%// didn't include that
fid = fopen(file_out, 'w');
fprintf(fid, '%s\n', x{:}); %// write output file
fclose(fid);

Answer 2

a = 1;
disp('Performing Action');
b = 2;
disp('Performing Action');
c = 3;
disp('Performing Action');
Or, if you can do this in a loop
for ii = 1:3
a(ii) = ii;
disp('Performing Action');
end
Actually making it output something after every line is not very matlab, but you could of course just loose all the semicolons and thus make it display all variables if you want to track where in the script you are.
I'd suggest a verbose switch in your code. Set it to 0 for no output and 1 for output (or use multiple levels if so desired)
if verbose > 0
disp('Performing Action');
end
This way you can easily switch the output on or off, depending on need.
For the code-reading and appending piece, see Louis Mendo's answer at https://stackoverflow.com/a/32137053/5211833

Answer 3

Here is my attempt. You can:
read the function line by line
execute each line, followed by your custom function.
NOTE
This won't work with functions containing for, if, etc..
You can eventually improve the code by passing a function handler with your custom action to runEachLine (and feval with that).
Here a code sample (partly based on this):
foo.m
function foo(args)
a = args{1};
b = 2;
c = a + b;
end
runEachLine.m
function runEachLine( mfile, args )
if nargin < 1
error('No script m-file specified.');
end
if ~strcmp(mfile(end-1:end),'.m')
mfile = [mfile '.m'];
end
if ~exist(mfile,'file')
error(['Cannot access ' mfile])
end
% Read function file
M = textread(mfile,'%s','delimiter','\n');
% Remove empty lines
M = M(~cellfun('isempty',M));
% Input arguments
assignin('base', 'args', args);
% Skipping first line: function [...] = func_name(...)
% Skipping last line : end
for k=2:length(M)-1
try
% Execute each line
evalin('base',M{k})
% Execute your custom function
disp(['Performing Action: ' M{k}]);
catch ME
error('RunFromTo:ScriptError',...
[ME.message '\n\nError in ==> ' mfile ' at ' num2str(k) '\n\t' M{k}]);
end
end
end
Usage:
>>runEachLine('foo.m', {4});
Result:
>> runEachLine('foo.m', {4})
Performing Action: a = args{1};
Performing Action: b = 2;
Performing Action: c = a + b;
>>

Answer 4

No, there is not.
What you present in your original question is just a simple usage of the = operator.
If you want to overload the default behaviour of MATLAB then you should consider creating a class and define the desired behaviour for each operator or function needed.