Call function inside another function - matlab

Question

I have a function
function toto(a,b)
[out,~] = evalc(a)
% here I would like to call another function
myFunc(x,y,file);
end
How could I pass this function as args to toto function as sometimes I want to call toto(a,b) and some other times toto(a,b,#()myFunc(x,y) ?

Answer 1

(Answer before question edit: assumes fixed number of inputs to toto)
If you want to call an arbitrary function from within function toto: first define a handle to that function:
f = #myFunc;
and then pass that handle as input argument to toto, so that you can use it within toto:
function toto(a,b,f)
[out,~] = evalc(a)
f(x,y,file); %// call function whose handle is f
end

Answer 2

Define your function with an input to pass a function handle:
function toto(a,b,fun)
...
% You must know how many inputs and outputs to expect
% but nargin and nargout do work for function handles
% so you can handle different cases if needed.
[y1,y2,...] = fun(x1,x2,...);
...
Call the function and pass in a handle to the function:
toto(a,b,#FunName)
Or:
FunHandle = #FunName;
toto(a,b,FunHandle)
You can pass in additional parameters by using an anonymous function:
Param = 'FileName';
AnonFunHandle = #(x1,x2)FunName(x1,x2,Param);
toto(a,b,AnonFunHandle)

Answer 3

If you want to be able to use both the toto(a,b) and toto(a,b,f) or similar function calls, you need to use varargin and nargin (and their output counterparts). Here is a very basic example; it ignores any more than two outputs or any more than three inputs, and does not do any input checking etc.
function [vargout] = toto(a,b,varargin)
if nargin >2
func = vargin{1};
fout = func(a,b);
else
fout = [] % if no third argument is given returns empty
end
if nargout > 0
varargout{1} = a+b;
end
if nargout > 1
varargout{2} = fout;
end
end
So for example you can call this as x = toto(2,3) (returns x = 5), [x y] = toto(2,3) (returns x = 5, y = []), [x y] = toto(2,3,#(x,y)(x*y)) (returns x = 5, y = 6).