MOPI provides a useful way to install dependencies for MATLAB and Octave.

There are two methods available to install dependency packages, one is the shell script mopi.sh, and the other is a MATLAB function mopi.m.

These lightweight utilities can be included in any MATLAB/Octave project which has non-trivial dependencies either by using a submodule of this repository, or including them as a static copy along with the LICENSE file, which can potentially be managed and updated using git subtree.

On *nix, one can download requirements specified in a file named requirements.txt with the bash script:

mopi.sh requirements.txt

On all systems, at the MATLAB or Octave command prompt one can do:

mopi('requirements.txt')

By default, the shell script will download packages into a folder called external in the present directory, whereas the .m function will ask for an installation destination using a command prompt.

To specify a download location at the terminal, one can need only provide it as a second input with

mopi.sh requirements.txt DOWLOAD_FOLDER

or equivalently

mopi('requirements.txt', DOWLOAD_FOLDER)

Each non-Forge package will be downloaded into a folder within DOWLOAD_FOLDER corresponding to the inferred name of the package.

The .m function for MATLAB and Octave can alternatively be given the name of a single package, or cell array of packages instead of a file listing packages.

mopi(PACKAGE_NAME)

The .m function can optionally add the downloaded packages to the path immediately (by default this is enabled).

This package offers three ways to install other MATLAB and Octave packages. These are

• from MATLAB FileExchange
• from Octave Forge
• from generic URL

Packages on MATLAB FileExchange should preferably be specified with the protocol scheme fex:https://. This should be followed by the FEX ID of the package. The FEX ID can be determined from the URL of the package, e.g. https://www.mathworks.com/matlabcentral/fileexchange/55540-dummy-package, or the File ID field on this page. In this case, the FEX ID is 55540.

For example, the package can be specified by

fex:https://55540

or alternatively, the name can be included, such as

fex:https://55540-dummy-package

which will be stripped out during processing.

Each FEX package will be installed into a folder matching the FEX ID of the package, such as 55540, with the downloaded contents unzipped into this folder.

If an entry does not have a protocol prefix, but is solely numeric (or numeric and then a hyphen) it is assumed to be a FEX package.

For example,

55540-dummy-package

is implicitly a FEX package and will be interpretted as such.

Packages on Octave Forge should preferably be specified with the protocol scheme forge:https://. This should be followed by the name of the package.

For example

forge:https://control

Forge requirements are ignored if the .m function is run on MATLAB instead of Octave. The shell script will install Forge dependencies only if a command octave can be found on the system, otherwise Forge dependencies are quietly ignored.

Care should be taken to make sure the packages are installed in the correct order, lest an error be thrown due to a missing dependency of a dependency.

For instance, the statistics package requires the io package, so in a requirements.txt file one should specify

forge:https://io
forge:https://statistics

and not

forge:https://statistics
forge:https://io

For example,

control

is implicitly a Forge package and will be interpretted as such.

All other protocols are handled the same way, and will be downloaded with wget or similar over HTTP, HTTPS, FTP, etc.

The name of the package is inferred from the (extensionless) filename which the URL points to. The package will then be installed into a subfolder matching this inferred package name. If the downloaded file is an archive it will be decompressed, otherwise it will be copied as-is.

For example,

https://www.mathworks.com/moler/ncm.zip

or

https://www.mathworks.com/moler/ncm.tar.gz

would both be decompressed into a folder ncm.

Comments can be inserted into requirements files by prepending them with a #. Entire lines can be commented out, or inline comments can be used. Inline comments must have a space separating them from actual content, lest the # be confused with a URL anchor

# This file contains a demo
fex:https://55540  # This is a dummy package

Here is an example file listing package requirements.

requirements.txt

# Requirements for package foo
forge:https://control
fex:https://55540-dummy-package
https://www.mathworks.com/moler/ncm.zip

If one wishes to only install requirements when they are needed in the code, the following method can be used:

if ~exist('dummy.txt', 'file')
    mopi('fex:https://55540');
end

There are a small number of differences between the shell and native matlab implementations of MOPI.

• The shell script can infer archives from their MIME type; the matlab function can only use file extensions.
• The shell script can unpack a wider variety of archive file types (provied an appropriate utility bash command is available); on MATLAB, the .m function is restricted to only .zip, .gz, .tar, (and .tar.gz or .tgz); on Octave, the .m function is restricted to .zip, .gz, .tar, .bz and .z.
• The shell script can save the downloaded files to a cache directory to use in future; the matlab function always discards downloaded files. This feature should be useful when repeatedly installing dependencies, for unit testing on a continous integration server such as Travis, say.
• The matlab function can optionally add the downloaded packages to the MATLAB/Octave search path; the shell script cannot.

To make dependency installation as easy as possible, it is prudent to ship a copy of MOPI along with any other toolbox or package you are developing which has any dependencies.

To set this up with a git repository, we recommend you use git-subtree. This is recommended over git submodule because submodule will require a deep clone of the repository for all the files to be in place, whereas subtree will include a copy of MOPI with your package even if it is downloaded as a zip file from the repository remote or FEX.

You can add mopi to your repository with the following command:

# Initial commit of MOPI
git subtree add --squash --prefix mopi \
    https://github.com/mopify/mopi.git master

And this can be kept up-to-date by merging new commits from the MOPI remote into your repository as follows:

# Updating MOPI
git pull
git subtree pull --squash --prefix mopi \
    https://github.com/mopify/mopi.git master
git push

Please note that you will need a clean working tree before attempting the subtree command.

Additionally, please note that the commit history cannot be rebased easily when it includes squashed changes.

MOPI was inspired by requireFEXpackage and pip.