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

[Paul Kienzle]

On Mar 13, 2005, at 10:25 AM, Alberto Francisco Martin Huertas wrote:
> Hello. I'm interested into source a m file in a C++ DLF function with 
> the
> following behaviour:
>
> $ cat script.m
> a=3;
> $ octave
> octave:1> a=1
> a=1
> octave:2> exfun ("script.m", "a")
> ans = 3
> octave:3> a
> a = 1
>
> and the exfun C++ function you have provided to me has this behaviour:
>
> $ cat script.m
> a=3;
> $ octave
> octave:1> a=1
> a=1
> octave:2> exfun ("script.m", "a")
> ans = 3
> octave:3> a
> a = 3
>
> so I would like to source a script having a local scope in my C++ 
> function. Is
> that posible ?

You still haven't answered why you would want to do such a thing.

Is it too difficult to put "function a=f" at the beginning of your
script so that it will have its own local symbol table?

Regardless, you can do what you are asking for as an m-file:

octave:1> function ret=exfun(f,v); source(f); eval(['ret=',v,';']); end
octave:2> a=1;
octave:3> exfun('script.m','a')
ans = 3
octave:4> a
a = 1

If you insist on doing so in C++, then you will have to reproduce
the work octave does when it sets up a function call context, such
as pushing the current symbol table and creating a new one, then
call the function to load and execute the script, then clear the
new symbol table and pop the old one.  You will have to dig through
the octave sources to see how.

- Paul



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