Matlab - Function taking no arguments within a class - matlab

Question

As I do not seem to be able to edit my old question (Matlab - Function taking no arguments but not static), here it is again:
I am trying to implement the following:
classdef asset
properties
name
values
end
methods
function AS = asset(name, values)
AS.name = name;
AS.values = values;
end
function out = somefunction1
ret = somefunction2(asset.values);
out = mean(ret);
return
end
function rets = somefunction2(vals)
n = length(vals);
rets = zeros(1,n-1);
for i=1:(n-1)
rets(i) = vals(i)/vals(i+1);
end
return
end
end
end
But I am getting the error that somefunction1 should be static. But if it's static then it can't access the properties anymore. How would I resolve this issue?
Basically I want to be able to write something like this:
AS = asset('testname',[1 2 3 4 5]);
output = AS.somefunction1();
as opposed to writing
AS = asset('testname',[1 2 3 4 5]);
output = AS.somefunction1(AS);

Answer 1

For accessing the properties of an object in a method, you need to pass that object as argument to the method. If you don't need a specific object in order to perform a function, then make it static (belongs to the class, but does not operate on a specific object).
So, compare the original code:
methods
% ...
function out = somefunction1
ret = somefunction2(asset.values);
out = mean(ret);
return
end;
function rets = somefunction2(vals)
n = length(vals);
rets = zeros(1,n-1);
for i=1:(n-1)
rets(i) = vals(i)/vals(i+1);
end
return
end
end
with the correct code:
methods
% ...
% this function needs an object to get the data from,
% so it's not static, and has the object as parameter.
function out = somefunction1(obj)
ret = asset.somefunction2(obj.values);
out = mean(ret);
end;
end;
methods(Static)
% this function doesn't depend on a specific object,
% so it's static.
function rets = somefunction2(vals)
n = length(vals);
rets = zeros(1,n-1);
for i=1:(n-1)
rets(i) = vals(i)/vals(i+1);
end;
end;
end;
To call the method, you'd write indeed (please test):
AS = asset('testname',[1 2 3 4 5]);
output = AS.somefunction1();
because, in MATLAB, this is 99.99% of cases equivalent to:
AS = asset('testname',[1 2 3 4 5]);
output = somefunction1(AS);
The differences appear when you're overriding subsref for the class, or when the object passed to the method is not the first in the argument list (but these are cases that you should not concern with for now, until you clarify the MATLAB class semantics).