Define shared subfunctions inside a classdef *.m file?

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I want to define a relatively small class (small enough that it makes sense to do everything inside of one file). I want to reuse a common subfunction between several methods, and having this subfunction inside of the classdef would make it cleaner, easily portable and automatically private. However, I have not been able to do so. Is there any way to accomplish it?
>> d = dummy;
>>??? Undefined function or variable 'my_pi'.
>>
>>Error in ==> dummy>dummy.dummy at 10
>> obj.dummy = my_pi();
dummy.m:
classdef dummy
properties
value;
end
methods
function y = my_pi()
y = 3.141592;
end
function obj = dummy()
obj.dummy = my_pi();
end
end
end

Accepted Answer

per isakson
per isakson on 21 Feb 2011
You can define subfunctions in the same file after the definition of the class, ie
classdef dummy
...
...
end % classdef
function out = subfun1( in )
...
end
/ per

More Answers (1)

David Young
David Young on 21 Feb 2011
Non-static methods require an object as the first argument, and as my_pi is not declared static and doesn't have an argument, it isn't found.
Rather than putting my_pi at the end of the file, I would include it properly in the class by declaring it to be static:
classdef dummy
properties
value;
end
methods
function obj = dummy()
obj.value = dummy.my_pi();
end
end
methods (Static)
function y = my_pi()
y = 3.141592;
end
end
end
You need to use the class name in the call to the static method. I've also corrected the assignment in the constructor: I assume that you intented to set the value property.
You could also set my_pi's access to private if you want it only to be visible from other methods of the class.
  8 Comments
Knut
Knut on 23 Feb 2011
@David:
Yes, I accepted the first reply before I saw yours, because it did solve my problem, your post just solved it more elegantly (for me). Now, I cant seem to change the acceptance.

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