Re: avoiding copying arguments by value when calling a function

[Sergei Steshenko]

--- On Mon, 8/20/12, Sergei Steshenko <address@hidden> wrote:

> From: Sergei Steshenko <address@hidden>
> Subject: avoiding copying arguments by value when calling a function
> To: address@hidden
> Date: Monday, August 20, 2012, 6:55 AM
> Hello,
> 
> if I understand correctly, if I write a function like this:
> 
> function result = foo(bar)
>   # function body goes here
> endfunction
> 
> and if I call the function this way
> 
> result = foo(bar);
> 
> , the 'bar' argument is copied by value each time 'foo' is
> called.
> 
> 
> I was thinking of something like this:
> 
> 
> bar_func = @() bar; # Octave accepts this
> 
> function result = foo(bar_func)
>   # function body goes here
>   # whenever I need 'bar' I use bar_func() instead
> endfunction
> 
> - I tried this and it works, i.e. produces the expected
> result.
> 
> If again I understand correctly, passing 'bar_func' is
> passing a function handle, which for large enough 'bar' data
> can hopefully yield better performance.
> 
> Are my understandings correct ? I.e. can anonymous functions
> be used as data wrappers in order to avoid physical copying
> of data ?
> 
> Thanks,
>   Sergei.
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> 

Or

bar_func = @() bar;

causes copying of 'bar' by value when 'bar_func' is called, so no performance 
gain is achieved ?

If that's the case, then what - global variables ?

Thanks,
  Sergei.