get list of subclasses

Question

Jonas Reber 2011-4-12

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/5304-get-list-of-subclasses

评论： Robin 2023-7-10

Hello Matlabers

I have a class "Filter" and some subclasses "xxFilter, "yyFilter", etc. They have a const property called "Name". I would now like to implement a funcation that gives me a list (Name) of all available classes that are subclasses of "Filter".

what I have so far:

flist = getAllFiles('myFilterFolder');
for i=1:numel(flist)
   [~,filename,fileext,~]=fileparts(flist{i}); % get those names
   if (exist(filename,'class') == 8) && (strcmp(fileext,'.m'))
      % -----------------------------------------------------------
      % here I would like to check if the class with name filename a class 
      % of type "Filter", if it would be an object, I would use
      % isa(filename,'Filter'). But how do I achieve this with a string?
      % -----------------------------------------------------------
      % then I could add the name (class with name filename).Name to my 
      % string list
   else
      flist{i}=[]; % empty the cell
   end
end
% cleanup empty cells
flist(cellfun(@isempty,flist)) = [];

As pointed out above I would like to check If there exists a class with name "filename" that is of type "Filter" just as I would do with "isa(.., 'Filter')".

I therefore need a function that allows me to access the class properties of tha class with a name given as a string (here filename)

Thank you so much!

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Answer 1

Jonas Reber 2011-4-12

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https://ww2.mathworks.cn/matlabcentral/answers/5304-get-list-of-subclasses#answer_7428

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I figured out how to resolve that problem when I realized the power of "eval()".

For anyone interested in doing something similar, here's the code I have now:

% list of all folders in FilterFunctions:
flist = getAllFiles('FilterFunctions');
% prepare result
filterlist = struct('Name',{},'Classname',{});
for i=1:numel(flist)
   [~,filename,fileext]=fileparts(flist{i}); % get just the filename
   if (exist(filename,'class') == 8) && (strcmp(fileext,'.m'))
      try 
         if(isa(eval(filename),'Filter'))
            filterlist(end+1) = struct( ... 
                 'Name', eval([filename '.Name']), ...
                 'Classname',filename ... 
                 );
         end
      catch % no problem - its eval
      end
   end
end

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Robin 2023-7-10

Nice solution!

Be aware though that this will not work if classes are defined in a package folder (starting with +).

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Answer 2

Yannick T 2011-4-20

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/5304-get-list-of-subclasses#answer_8205

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Hello Jonas,

I was trying to do something similar and your solution works fine. You could also do it in a slightly different way which doesn't require the use of eval():

if exist(filename, 'class') && ismember('Filter', superclasses(filename))
  filterlist(end+1) = struct( ... 
      'Name', eval([filename '.Name']), ...
      'Classname',filename ... 
  );
end