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License files from the FEX

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Jan
Jan on 18 Jun 2012
Commented: Steven Lord on 28 Jun 2018
FEX submissions are accompanied by a file called "license.txt", which contains the name of the author. You can copy the files of a submission to a specific folder and include if in the Matlab path.
When a user downloads 100 submissions, there are two methods:
  • Either 100 folders are added to the path. This increases the danger of getting the strange and frequent "exhausted change notification handles" problems, see Solution 1-18IFI.
  • Save the functions to one folder and overwrite the license files. This does collide with the BSD license conditions.
Especially when I think about a tool, which automatically resolves dependencies to other FEX submissions, the pile of equivocal license files is a tedious obstacle. How can this problem be solved considering the large number of already existing submissions?

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Accepted Answer

Daniel Shub
Daniel Shub on 19 Jun 2012
You could download each FEX submission to a separate folder and then create links (hard or symbolic) to the MATLAB files (m, p, mex, etc.) in a single common folder for all FEX submissions. This might cause problems with name collisions to common files (e.g., contents.m).

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Jan
Jan on 20 Jun 2012
The links are a good idea. The contents.m file is no problem here, because it should be re-created dynamically and contain the names of all functions contained inside a folder.
One problem is, that some submissions *require* specific subfolders, such that adding the folder to the PATH is obligatory. Therefore a full automatic package mamagement is not possible currently. However, the usability of the FEX is *decreasing* with a growing number of submissions, as long as there is no management function which resolves the depenencies.

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More Answers (2)

Jan
Jan on 20 Jun 2012
The license.txt files could be renamed by appending the name of the submission, e.g. "licence.txt" to "license_typecast_.txt" for James' important, efficient and useful helper function FEX: 17476.
A lot of users are overwhelmed by the installation procedures of some submissions. I include a "please compile the code by mex -O abc.c before the first run" in the help section of the code, but I still get more questions for clarifications about the MEX command than comments or ratings. Therefore I hesitate to force the user to download and install another function and compile it in addition.

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DGM
DGM on 28 Jun 2018
When I first ran into it, I really found it hard to believe that the license collision problem had existed, let alone that it's existed for so long.
I've been adding suffixes to the license files as you describe. It seems like the only reasonable workaround.
Jan
Jan on 28 Jun 2018
SPDX is a nice and efficient solution:
% Copyright [year], [project founder], [project name], [contributors]
% SPDX-License-Identifier: BSD-2-Clause
% http://www.opensource.org/licenses/BSD-2-Clause
If this is inserted in the help section of each M and C file, every thing is fine and clear. Then an additional license.txt is not required.
Steven Lord
Steven Lord on 28 Jun 2018
Consider using the Add-On Explorer to have MATLAB download and manage add-ons. If you do this, I believe it puts each in a separate directory to avoid potential conflicts like the license.txt files.

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Malcolm Lidierth
Malcolm Lidierth on 22 May 2013
@Jan
I find lots of "installation procedure" enquiries also even though clear install instructions are provided. Often that is because users have read "between-the-lines" instead of taking the instructions literally - and their interpretation can be understandable e.g I see how a 10 year old caveat that "you must use "save -v6" might be interpreted as use "save -v[6 or 7]" in 2013.
For Waterloo, which has many files/folders/classes, I wrote a short script that uses MATLAB to do the download, unzip the files and set up the MATLAB and Java path - providing a few command line prompts/questions - in the present context that might be e.g "Have you run mex -setup before? If not do you want to run it now? [y/N]:"
Maybe the FEX should include an o[tional "Installation Script" button as well as a "Download Button" - providing script code to cut-and-paste into the Command Window when clicked, that could do this.

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Jan
Jan on 22 May 2013
Thanks for your answer, Malcolm. In modern matlab versions the mex() command can reply, if the setup has been performed already. Unfortunately you cannot rely on FEX users to run a modern matlab version.
The install mechanism for Waterloo is fine for 99% of the cases. I do not have an internet connection on my Matlab computer to secure the stored patient data. Then an automatic downloading must fail, but it is impossible to guarantee a comfortable and flexible solution for all setups.

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