overload subsref locally in a function

Is it possible to overload subsref locally in a function? I want to do it locally because the definition will involve calls to Matlab's subsref.

I tried:

a = [1 2 3];

subsref = @(varargin) disp('hello');

but a(1) doesn't output "hello".

I know this is a trivial example, but the actual goal is to define: subsref = @() SOMETHING-COMPLICATED and make use of the flexibility of the expression: a(1,2,:).field, instead of calling subsref(a,substruct(...)), which is complicated.

Thank you!