Using two versions of matlab code - how to handle paths?

Question

I would like to use two versions of the same Matlab software package at the same time (I would like to compare their outputs for testing). The package modifies the path so that functions in subdirectories can be found. This seems problematic since the package assumes that it is the only copy running on the machine. The path is essentially a global variable which is unintentionally shared between the two copies of the code.

Example simplified code structure:

/main_code.m
/compare_results.m
/code_a/somefn.m
/code_a/submethods/
/code_b/somefn.m
/code_b/submethods/

Note that somefn.m adds the submethods directory to the path, and calls code from the submethods folder by relying on the path.

Example of code that I would like to run:

for i = 1:1000000
    % Run version A:
    result_a = code_a.somefn(i);
    % Run version B:
    result_b = code_b.somefn(i);
    % Compare the output from the two versions:
    compare_results(a,b);
end

One solution that I can think of is to manually update the Matlab path every time that I want to switch to a different version of the package. This seems like unnecessary coding overhead, and potentially a performance problem (due to switching the path so often).

Another solution might be to rewrite the code to be object oriented, so that the functions are attached to objects, and I can create objects of different versions. The problem with this is that in reality the code package contains hundreds of files, and I was not the original author so rewriting would be a huge task .

(Yet another option would be to change directory all the time, so that the code to run is always in the current directory. This would be so much of a headache due to the number of subfolders that I do not think this is a serious solution. It also has potential performance overhead drawbacks similar to always changing the path.)

Is there a cleaner way to handle this? Can I somehow specify the folder of the code that I want to run? What is the best way to design such a code package so that this problem does not come up?

user_996405 · Answer

Just create packages, which can contain functions with the same names: Packages Create Namespaces

Basically create two folders named, say, +package1 and +package2. The "+" in the folder name is important. Then place your functions under both of them, say, foo.m. Then, you can call each separately without messing with MATLAB path as:

>> package1.foo
>> package2.foo

user_6579744 · Answer

You can use private functions. Change the directory structure as:

/main_code.m
/compare_results.m
/+code_a/somefn.m
/+code_a/private/
/+code_b/somefn.m
/+code_b/private/

Each somefn has access to the functions contained in its private sub-folder. So there is no need to create global variable and to add private sub-folders to the path.

Using two versions of matlab code - how to handle paths?

2 Answers