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LizardSpock

Name Spacing in Matlab

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A typical work flow in Matlab involves a folder filled with scripts and functions. Over time this folder grows until it becomes completely unmaintainable and dependencies between scripts can not be tracked.

The next step is to group the related functions into folders in maintainable collections. They can then be added to the scripts that require them by adding to Matlabs search path via:

addpath('../collection_of_functions_a/');
addpath('../collection_of_functions_b/');

The main issue I have with this is that of name spacing when working with third party functions or developing your own it would be easy to override other functions even internal ones. For toolbox developers it is hard to known all the function names from matlabs toolboxes. After a name collision which one is picked up is dependent on the path order. Other languages often use name spacing to avoid these name conflicts.

Since MATLAB Version 7.6 Packages have been available for just this, adding name spacing to classes, but it also works for raw (plain) functions.

To create a package, as before place functions in a folder, start the folder name with a +, ie +mypkg then you have created package mypkg.

To use the package functions in a script they must be imported.

import mypkg.*

%% call function_x
a = mypkg.function_x() ;

As packages themselves can not be on the path you have to make the parent folder accessible.

If you have a folder containing a lot of packages then this is quite useful. Add one folder to path then import the required packages.

If the packages are being independently maintained then it is likely that they all have separate hierarchy (I think this is good from a development point of view). To avoid adding unnecessary items to your search path I would recommend a hierarchy of:

Top_level_package
  function
  +my_pkg
    function_x.m
    function_y.m
  test
    run_test_function_x.m
    run_test_function_y.m

run_test_function_x.m :

addpath('../function/');
import my_pkg.function_x

%% test function_x
% ...

The downside of this is that every package needs an addpath and import. Which you will have unless all your packages live under one parent directory.

An excerpt from What is in the Matlab Search Path:

The userpath folder is first on the search path, above the folders supplied by MathWorks. By default, MATLAB adds the userpath folder to the search path at startup. Therefore, the userpath is convenient for storing files where MATLAB can access them.

The userpath consists of a primary path, and on Macintosh and UNIX® platforms, it also contains a secondary path. The primary path is only one folder, but the secondary path can contain multiple folders.

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