Modifying global variables from within functions

[John W. Eaton]

On 13-Nov-2001, Roberto Hernandez <address@hidden> wrote:

| I am trying to modify a global variable directly from within a function. 
|   The solution I found is somewhat complicated for what I want. I was 
| wondering if there's a better way to do it.
| 
| Here's the situation. The function "foo" has to accept a global variable 
| name and a value and assign the value to the variable.
| 
| For example this function:
| 
| ------------------------------
| function foo(varName, newValue)
|      eval(["global ",  varName]);
| 
|      if isnumeric(newValue)
|          eval([varName, " = " , num2str(newValue), ";"])
|      else
|          eval([varName, " = \"" , newValue, "\";"])
|      endif
| endfunction
| ------------------------------
| 
| So I would call it this way:
| 
| ------------------------------
| octave:1> global a
| octave:2> foo("a", 5)
| ans = 5
| octave:3> foo("a", "hello")
| ans = hello
| ------------------------------
| 
| The previous example works fine. But if I want to do more complex 
| operations inside the function "foo", then having to use "eval" and 
| building lots of strings becomes annoying. It's easy to make mistakes 
| and pretty bad for debugging.
| 
| The question is: Is there a better way to do this?

How about

  function foo (__n__, __v__)
    eval (sprintf ("global %s; %s = __v__;", __n__, __n__));
  endfunction

??

jwe



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