Assignin variables in a stand-alone application

Question

Santosh Tiwari 2018-9-8

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/418110-assignin-variables-in-a-stand-alone-application

评论： Walter Roberson 2018-9-8

I am creating a stand-alone application using "mcc -mv foo.m" for my matlab code. In my code, I am using "assignin('base',var_name,var_value)" to assign value to variables. I read the variable values from a file and then assign those values to respective variables. What I am finding is that when I run the created executable, it actually remembers the old values that I had used during development/testing. How is it possible? Does mcc include workspace variables and their values at the time of creating stand-alone executables and does not override their values by assignin? I am currently using Matlab 2017a. My code has worked fine with 2014a in the past. I am using Matlab on Linux.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2018-9-8

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/418110-assignin-variables-in-a-stand-alone-application#answer_335948

No, see https://www.mathworks.com/help/compiler/excel/matlab-data-file-mat-files.html

However, when you have a load() of statically named .mat file, then the .mat file is included in the archive, and that will be the file that is read from unless you take specific steps to read from a different file. In particular, if you load() a .mat then the current directory of the user running the executable will not be examined for the .mat file.

The current directory of a compiled executable is not going to be the user's directory unless you take care to figure out where the user's directory is and cd to there (such as by examining the HOME environment variable.) Furthermore when you load() from a file name with no path given, MATLAB always looks in the archive for the file first: to disable that you need to give the path at load() time.

https://blogs.mathworks.com/loren/2008/08/11/path-management-in-deployed-applications/

6 个评论
显示 4更早的评论隐藏 4更早的评论

Walter Roberson 2018-9-8

Where is param.csv expected to be read from?

Either standard dependency analysis or manually adding it to the archive with -a flag would cause a copy of your param.csv to be added to the archive in the ctfroot() directory. And since you did not provide a path to the file in the fopen(), no matter which directory you are cd'd to, fopen() in a compiled application will always look in ctfroot() first to try to find the file. This is a behavior for compiled executables that overrides the standard MATLAB behavior to look in the current directory first.

If you want to read from a user-provided param.csv, then you need to figure out where that file is, and you need to fullfile() to construct the complete path to the file, and fopen() that complete path.

If you generated a "graphics app" instead of a "console app", then the current directory of at the time of execution will have absolutely nothing to do with the user's current directory at the time they started the .exe, even if they stated the exe from windows command line instead of by double-clicking to execute the file. The concept of the current directory for the user if they double click the file to execute it has no meaning: the user might have a dozen different shells open at the time of double-clicking, each with its own current directory, so "graphics apps" ignore anything except themselves (and the settings configured in the icon) for the purpose of "current directory" at startup.

Santosh Tiwari 2018-9-8

OK. Thanks for the explanation. This is probably the most likely cause. I have not specified the path in the fopen(), just the file name. I assumed fopen() will first lookup in the current directory; but you are telling me that it will check ctfroot() first. For a standalone executable, this is probably the archive and mcc pulls in the file if it finds it during compilation.

Walter Roberson 2018-9-8

在 MATLAB Online 中打开

Right. And most of the time "current directory" in a compiled archive is not where you think it is.

If you hardcode a cd to a particular directory like

cd('C:\Program Files\Tiwariware\Megaosh')

then you have the problem that the user might have installed somewhere else or that the local drive might be reserved by IT for the operating system and all user files might have to go on a network drive.

You might want to look at https://www.mathworks.com/matlabcentral/fileexchange/15885-get-user-home-directory

请先登录，再进行评论。