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How can I access the methods of a returned object?

Asked by Alex Henderson on 13 Nov 2014
Latest activity Answered by Philip Borghesani on 25 Nov 2014
I'd like to achieve the following, but don't know if it's possible.
I have a function that returns an object of a class. The returned object has a method. I'd like to access the method inline.
For example, say I have a class called myclass, with a method called classmethod. I also have a standalone function, myfunc, that takes a numeric argument and returns an instance of myclass. If I say...
obj = myfunc(123);
obj.classmethod();
...then everything is fine, although the workspace now has an additional variable (obj). Is it possible to say the following?
myfunc(123).classmethod();
I keep getting this error "??? Undefined variable "myfunc" or class "myfunc"."
Thanks, Alex

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2 Answers

Answer by Titus Edelhofer on 13 Nov 2014
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Hi,
no, that's not possible. It's like with numeric arrays: you can't index into the result of a function directly. Suppose your myfunc returns a matrix.
myfunc(123)(1)
would not work either...
You could of course encapsulate this into some function that combines those two steps, but I doubt that makes sense.
By the way it looks weird to me that you create an object, want to call one method only and apparently have no use for the object afterwards? Nothing wrong with it per se, but seems not typical to me.
Titus

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Hi Titus,
Ah that's a shame. Thanks for the information.
My use of the temporary object in this example is to generate class specific code for display (or some other procedure that doesn't return a variable). The temporary object is a storage class output from the previous function. I hoped to daisychain a collection of free functions that take different storage classes, and output other storage classes, where each storage class would know how to handle display etc.
Thanks for your help,
Alex

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Answer by Philip Borghesani on 25 Nov 2014

Don't use dot to call the method:
classmethod(myfunc(123));
In MATLAB with standard objects there is no difference between obj.method(...) and method(obj,...) .
*By standard objects I mean one that does not have an overloaded subsref function.

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