Re: doubts about functions declared in parse.h ...

[Geraint Paul Bevan]

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Alberto Francisco Martin Huertas wrote:

| I would like the following behaviour in a Octave session:
|
| octave:1> A=1
| A = 1
| octave:2> example_function()
| ans = 3
| octave:2> A
| A = 1
|
| Thanks for your help, Alberto.


It is normal Octave behaviour to limit the scope of variables to the
calling function,


assignment.m:
A = 3


example_function.m:
function retval = example_function ()
~  assignment;
~  retval = A;
endfunction


octave> A = 1
A = 1
octave> example_function
A = 3
ans = 3
octave> A
A = 1


However, there is no way (as far as I am aware) of using a *script* such
as "assignment.m" to assign values to variables within a DLD. The Octave
environment is separate from the C++ dynamic function.

If you need to get values from an m-file, you could create a function
which returns them,


assign_A.m:
function retval = assign_A ()
A = 3   # you could call assignment.m here, instead
retval = A;
endfunction


example_function.cc:
#include <octave/oct.h>
#include <octave/parse.h>
DEFUN_DLD(example_function, args, , "demo")
{
~  octave_value_list retval;
~  octave_value A = feval("assign_A")(0).double_value();
~  retval(0) = A;
~  return retval;
}


octave> A = 1
A = 1
octave> example_function
A = 3
ans = 3
octave> A
A = 1


- --
Geraint Bevan
http://www.mech.gla.ac.uk/~gbevan

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