How to solve function overloading on Octave from different folders but with the same name?

Question

The naming used here as function1, Root, class1 and class2 are just fictitious and does not exist in the code. They are just here to mask their real names, however they explicily represent how the files are disposed on the files system and how they are being called.

There are folders called Root, Root/class1 and Root/class2.
There are the files called Root/class1/function1.m and Root/class2/function1.m.
On these files there are the functions function function1( A ) and function function1( A, B ), respectively.

Now I am on the folder Root/class2 running a file called system.m and I do:

addpath( '../class1' )
function1( A )

And it tries to call the function function1( A, B) from the file Root/class2/function1.m instead of call the function function function1( A ) from the file Root/class1, outputting the error:

error: 'B' undefined near line 4 column 27

How to call the function function function1( A ) from the file Root/class1/function1.m while running a file from the folder Root/class2 overloading the function within the current "context"?

I want to call a function from another folder, but over there, it has the same name as a function within the current folder.

I suppose it's too simple to suggest not using the same function names for two different functions? — Adriaan, Aug 29 '16 at 22:31
@RockNinja, just in case this is a case of [XY Problem](http://xyproblem.info), what are you actually trying to achieve? There are several ways of introducing a namespace, if that's what you're trying to do ... — Tasos Papastylianou, Aug 29 '16 at 22:33
I would have to do the ugly thing as: `Root/class1/class1_function.m` and `Root/class1/class2_function.m`. So, if there is a way to avoid such name prefixing on the file/function name would be good. — Evandro Coan, Aug 29 '16 at 22:33
Well, there is a simple way: give reasonable names to function instead of naming everything `function`... So e.g. when you have a special summation call it `WeightedSum` instead of `function`. And please, do not overwrite reserved keywords like `function`, as that will mess up your MATLAB instance when trying to use the keyword for what it has been intended. — Adriaan, Aug 29 '16 at 22:34
@RockNinja: matlab supports fully object-oriented programming. Are you trying to create objects with methods? — Tasos Papastylianou, Aug 29 '16 at 22:39
@TasosPapastylianou, it is just Octave, I want to call a function from another folder, but over there, it has the same name as a function within the current folder. — Evandro Coan, Aug 29 '16 at 22:42
you really need to provide a minimal working example here ... is this your code entirely? can you rename the functions? can you make them into a package? can you make them class methods? In general you cannot have two functions with the same name on the active path. If you *really* must do it this way, then `cd` to the other function's directory and then go back to where you were. — Tasos Papastylianou, Aug 29 '16 at 22:45

Tasos Papastylianou · Accepted Answer · 2016-08-29T23:26:37.503

You're not giving us much information. It all depends why you're doing this, and whether you're the one developing / using this code.

But in general, you should NOT be adding folders containing functions with the same name to the current working path. And you should most definitely NOT use the word "function" as a name for a function, since that will shadow the function keyword and all hell breaks loose.

Here's a few suggestions on how to do what you're trying to do:

Option 1
For instance, you could convert your functions into static class methods:

% in file class1.m:
classdef class1
  methods(Static)
    function myfunction(A)
      fprintf('Hello from class1: A is %d\n', A);
    end
  end
end

% in file class2.m
classdef class2
  methods(Static)
    function myfunction(A,B); 
      fprintf('Hello from class2: A is %d and B is %d\n', A, B);
    end
  end
end

% at the terminal:
>> class1.myfunction(5)
Hello from class1: A is 5
>> class2.myfunction(5, 3)
Hello from class2: A is 5 and B is 3

Option 2
Or, if all you want is a namespace, you could rename your Root/class1/myfunction.m into Root/+class1/myfunction.m. The "plus" makes that folder a "package", which means you can do this (from the Root folder):

class1.myfunction(5);
class2.myfunction(5,3);

Option 3
If you really must do this with normal functions in folders etc, then instead of adding "class1" to the path, just cd to it instead, use your function from that directory, and then cd back to where you were. E.g, say you have a folder Root/class1 with file myfunction.m, and folder Root/class2 with files myfunction.m and myscript.m. Then in myscript.m you write:

% go to class1 directory to use the conflicting function
cd '../class1'
myfunction(5)

% come back to class2
cd '../class2'
myfunction(5, 3 )

However, please note that this is the least recommended method! since it could go horribly wrong! (e.g. if one of the functions changes directories or relies on a particular folder structure, etc.)

How to solve function overloading on Octave from different folders but with the same name?

1 Answers1