Class definition not updated after path change
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Hi,
I'm having trouble with class definition update when I change Matlab path within a script.
Let's illustrate with a simple exemple.
I have these folders in my workspace, none of them are in the Matlab path.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/194101/image.png)
The myClass class is as simple as it can be. The one in the FolderA is defied as below :
classdef myClass
properties
FolderAprop
end
end
And the one in FolderB :
classdef myClass
properties
FolderBprop
end
end
When I change the Matlab path to use the FolderB class instead of Forlder A class within a script, the class definition doesn't updates if one instance of the class is in the workspace. The code below, all within a script called testClassUpdate.m, shows it :
clear all
addpath ./FolderA
which myClass
myClassInstA = myClass;
properties(myClassInstA)
rmpath ./FolderA
addpath ./FolderB
which myClass
myClassInstB = myClass;
properties(myClassInstB)
rmpath ./FolderB
It returns :
>> testClassUpdate
L:\tmp\TestPathClass\FolderA\@myClass\myClass.m % myClass constructor
Properties for class myClass:
FolderAprop
L:\tmp\TestPathClass\FolderB\@myClass\myClass.m % myClass constructor
Properties for class myClass:
FolderAprop
But when I execute the exact same code in two times, returning the the prompt after addpath ./FolderB, it works as expected :
>> clear all
addpath ./FolderA
which myClass
myClassInstA = myClass;
properties(myClassInstA)
rmpath ./FolderA
addpath ./FolderB
L:\tmp\TestPathClass\FolderA\@myClass\myClass.m % myClass constructor
Properties for class myClass:
FolderAprop
>> which myClass
myClassInstB = myClass;
properties(myClassInstB)
rmpath ./FolderB
L:\tmp\TestPathClass\FolderB\@myClass\myClass.m % myClass constructor
Properties for class myClass:
FolderBprop
I tried to call the rehash function but it has no effect. If I clear all instances of myClass after changing path, it works as expected but I try to avoid that.
I read the two following help pages and, if I understand correctly, the class definition should have been updated as I put my class files in @ folders.
Do anyone knows how to get my class definition updated correctly ?
Regards,
Julien
0 Commenti
Risposte (1)
per isakson
il 9 Nov 2018
I have reproduced the behavior on R2018a.
The following script
%%testClassUpdate
clear all
addpath ./FolderA
[~] = which('myClass');
myClassInstA = myClass;
disp( properties(myClassInstA) )
clear myClass
rmpath ./FolderA
addpath ./FolderB
[~] = which('myClass');
myClassInstB = myClass;
disp( properties(myClassInstB) )
rmpath ./FolderB
When I run the entire script in one go (F5) it displays
'FolderAprop'
'FolderAprop'
However, when I run it section by section (Cntrl+Shift+Enter) it displays
'FolderAprop'
'FolderBprop'
I get identical results even without the clear myClass
IMO: This is a case for Tech Support.
1 Commento
Christoph Hüsson
il 26 Gen 2023
Modificato: per isakson
il 4 Feb 2023
i ran into the same issue. you need to clear existing variables that use type-definitions you are about to update. read this, especially the section "Changing Path to Update Class Definition":
I am using sth like this to remove only those workspace variables, which would potentially be affected:
currVars = evalin('base', 'whos');
zimVars = {};
for v = 1:length(currVars)
if startsWith(currVars(v).class, 'ZimV.')
zimVars{end + 1} = currVars(v).name;
end
end
if ~isempty(zimVars)
if ~NameValueArgs.keepConflictingVaraibles
% https://stackoverflow.com/questions/20167762/evalin-with-variable-matlab
% required because we are going to remove them from inside a evalin-call
assignin('base', 'zimVars', zimVars);
warning('Removing variables from your workspace that require classes of this package. If you do NOT want this for future calls, use keepConflictingVaraibles=true')
evalin('base', 'clear(zimVars{:}); clear zimVars');
else
warning('There are variables in your workspace that require updates to class-definitions of this package. You might experience unexpected behavior, as existing variables might use stale definitions. Read more about this here (especially section "Changing Path to Update Class Definition"): https://de.mathworks.com/help/matlab/matlab_oop/organizing-classes-in-folders.html')
end
end
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