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RE: setting global variables

From: Richardson, Anthony
Subject: RE: setting global variables
Date: Fri, 26 Oct 2018 18:05:59 +0000

> To: Help GNU Octave <address@hidden>
> Subject: setting global variables
> I have been using the "global" directive to set up some (around 50) global 
> variables in a script. However in order to access them from functions in the 
> > same script, I need to define them as global again or they are not defined 
> in the function.
>     Seems a bit redundant to me--is there some way to define variables share 
> by all functions just once?
> Thanks
> Fritz

You can achieve a similar effect (although perhaps not quite as convenient) by 
using a persistent struct inside a data retrieval function.  I use a function 
named simState() for this purpose.

To define and set the value of variable from within one function or script:
   simState("TMAX", 1200.)
Then to retrieve the value from within any other function:
   TMAX = simState("TMAX")

I have included simState() below.    I use it for a purpose like what you 
describe.  I want to access a global variable from multiple functions.  Note 
that I retrieve a copy of the "global" value.  If I want to change the global 
value, I need to use simState("TMAX", newvalue).

Tony Richardson

function v = simState(key, val)
  persistent state;
  if (nargin == 0)  
    % Return the entire struct
    v = state;
  elseif (nargin == 1)
    % Return a particular field from the struct
    v = state.(key);
  elseif (nargin == 2)
    % Set a key value (key must be a string)
    state.(key) = val;
    v = val;

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