CODEWITHSUNDEEP
octave
LogarithmicEagle
LogarithmicEagle

Reputation: 43

How to make a function file in Ocatve with multiple functions

I know that you can make a function file in Octave in which the file name is the same as the function which defines one function, but I would like to define multiple functions in one file. Is there any way to do this, or do I need a separate file for each function.

Upvotes: 1

Views: 2044

Answers (1)

Tasos Papastylianou
Tasos Papastylianou

Reputation: 22215

In this answer I will assume that your main objective is a tidy workspace rather than explicitly a one-file requirement.

Let's get the one-file approach out of the way. You can create a script m-file (not a function m-file), and define a number of command-line functions there. The octave manual has a section on this. Here's an example:

% in file loadfunctionDefinitions.m
1;   % statement with side-effect, to mark this file as a script. See docs.
function Out = Return1(); Out = 1; end
function Out = Return2(); Out = 2; end
% ... etc


% in your main octave session / main script:
X = Return1() + Return2();

However, this is generally not recommended. Especially if you would require matlab compatible code, since matlab introduced 'script-local functions' much later than octave, and decided to do it in a manner incompatible to the existing octave implementation: matlab expects script-local functions to be defined at the end of the script; octave expects them to be defined before first use. However, if you use normal function files, everything is fine.

While I appreciate the "I don't like a folder full of functions" sentiment, the one-function-per-file approach actually has a lot of benefits (especially if you program from the terminal, which makes a wealth of tools twice as useful). E.g. you can easily use grep to find which functions make use of a particular variable. Or compare changes in individual functions from different commits, etc.

Typically the problem is more one of having such function files littering the directory, when other important files are present, e.g. data etc, and having so many files in one place makes finding what you want hard to spot, and feels untidy. But rather than have a single file with command-line definitions, there are a number of other approaches you can take, which are probably also better from a programmatic point of view, e.g.:

  • Simply create a 'helper functions' folder, and add it to your path.
  • Use subfunctions in your main functions whenever this is appropriate, to minimize the number of unnecessary files
  • Use a private functions folder
  • Use a 'package directory', i.e. a folder starting with the character '+', which creates a namespace for the functions contained inside. E.g. ~/+MyFunctions/myfun.m would be accessed from ~/ via MyFunctions.myfun(), without having to add +MyFunctions to the path (in fact you're not supposed to).
  • Create a proper class directory, and make your functions methods of that class

The last option may also achieve a one-file solution, if you use a newer-style classdef based class, which allows you to define methods in the same file as the class definition. Note however that octave-support for classdef-defined classes is still somewhat limited.

Upvotes: 5

Related Questions