array of objects

Hi, have a class like this

   classdef someClass
      properties
         name
         value
       end

      methods
         function obj = someClass(name)
            obj.name(name)
      end
   end

I would like to create an array of objects of that class. So if I have the names= ('a','b','c') I would like to have an array a of 3 objects with a(1).name='a' a(2).name='b' a(3).name='c'

how do I have to structure my constructor to achieve this by calling

a(1:numel(names))=someClass(names)

or how can I do this in another halfway smart way. Thanks, C

Answer 1

[Titus Edelhofer]

Hi,

something like this?

classdef someClass
  properties
      name
      value
  end
  methods
      function obj = someClass(name)
          if ~nargin
              % the default constructor. Needed for array creation
              obj.name = '';
          else
              % only take care of the array part for simplicity:
              if iscell(name)
                  [obj(1:length(name)).name] = deal(name{:});
              end
          end
      end
  end
end

You can call then as

a = someClass({'a' 'b' 'c'});

Titus

[Christof]

Thanks a lot Titus, this works great. However, i run into troubles when I want to do more than assign just the names in the constructor, as the constructor now seems to be called twice (independent of the number of elements in the name cell). Does anyone have an idea why that is?

So, if I add the line

display('object created')

I get the following output

>> a = someClass({'a' 'b' 'c' 'd' 'e'});

object created

object created

[Titus Edelhofer]

Yes, that's right: if you use the debugger, you see, that in the first call the constructor is called without input argument (the default constructor). This is needed to construct the object itself (without parameters). The second call constructs the individual objects using the parameter "name". So: put into the if ~nargin the default values, whereas the "real" construction is in the else-part. If that answers the question, you might mark the question as answered ;-).

[Sean de Wolski]

Nice Titus, learn something every day!

[Kye Taylor]

When I debug, I see that the first call is with input, and the second call is without. Is my debugger being fishy, or is something nonconstant across machines?