MATLAB: Equivalent of function handle for scripts

handlesscript

Dear all,
I am currently working in a project for which I would like to create an equivalent of function handles for scripts. To be more precise: I have a code at the beginning of which the user sets a few options before an algorithm with a large number of repetitions runs. Depending on the options chosen at the beginning of the code, one script will be selected among several (say for instance among script1 and script2), and this script will then be run at every repetition of the algorithm.
So of course one option is to use an "if" statement within the algorithm: at every iteration the "if" statement selects the desired script and executes it. But I am afraid that the "if" statement repeated at every iteration might slow down the code (I may have a few millions of repetitions). Ideally, I would like to create some command that assign a handle to the correct script at the beginning of the code, before the algorithm starts. For instance, if the options select script 1, assign myscript=@script1. If conversely the options select script2, then assign myscript=@script2. In both cases, the algorithm only has to call for myscript, without further if statement.
I tried to use the handle @ on my scripts but it fails: handles defined this way seem to be only calling for functions. It seems also that replacing my scripts with functions to use regular handles is not an option: the scripts (turned into functions) would call for different arguments, and different numbers of arguments. So I would again have to use "if" statements at each iteration to vary the list of arguments. I cannot either use functions without inputs nor outputs since the commands implemented by the scripts have to update variables in the global space.
So at the moment I am stuck. I did not imagine that I would struggle with something as simple as assigning a handle to a script, but it seems that Matlab really can't do that. Anyone has a solution for this? Or is the "if" statement the best solution in the end?
Thanks a lot
edit: simple worked example
 % script1.m

 x=x+y*z;
 % script2.m

 x=x-w;
 % code.m

 x=1;
 % options: choice of script (1 for script1, 2 for script2)

 choice=1;
 % variables generated by the choice

 if choice==1
 y=1;
 z=2;
 elseif choice==2
 w=0.5;
 end
 % algorithm

 for i=1:10000000
    % if statement
    if choice==1
    script1
    elseif choice==2
    script2
    end
 end
Ideally replace with:
 % script1.m
 x=x+y*z;
 % script2.m
 x=x-w;
 % code.m
 x=1;
 % options: choice of script (1 for script1, 2 for script2)
 choice=1;
 % variables generated by the choice
 if choice==1
 y=1;
 z=2;
 myscript=@script1
 elseif choice==2
 w=0.5;
 myscript=@script2
 end
 % algorithm
 for i=1:10000000
 myscript
 end

Best Answer

No script handle needed at all.
listOfScriptNames = {'script1', 'script2', 'otherboringscript', 'myreallyinterestingscript'};
Now, when you use this, you will have some script chosen, as a number, from 1:4.
So lets say that you have somewhere in your code identified the number of that script as:
scriptNumber = 4;
It may have come from a menu choice, thus a callback, or whatever. You can use that script as easily as this:
eval(listOfScriptNames{scriptNumber})
While I try mightily to avoid use of eval, it is not the end of the world when you are forced to use it on a limited basis.
Ok, do you really, absolutely insist on creating this as a function handle? So something you can pass around at will? Sigh. Ok, I found a way to do it. You need to use str2func. Try this:
I've created a script on my search path with the name myreallyinterestingscript.m. You can see it here:
>> type myreallyinterestingscript.m
% My really interesting script
disp('Help! The sky is falling!')
Ok, not that interesting. In fact, boring as it can be. But it is 5 am here, and I'm not feeling that creative.
scriptnumber = 4;
f = str2func(listOfScriptNames{scriptNumber});
Now, can I use it as a function handle? No problem.
>> f()
Help! The sky is falling!
>> f()
Help! The sky is falling!
>> f()
Help! The sky is falling!
I can pass f around as the argument to a function, anything at all. Just evaluate it as f().
If you try to just use it without the parens,
f
f =
  function_handle with value:
    @myreallyinterestingscript
it just dumps the contents of the function handle to the command window. So remember to use it as f().
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