[Octave-bug-tracker] [bug #52980] clear in the caller workspace doesn't clear all references to a variable.

[Philip Nienhuis]

Update of bug #52980 (project octave):

                  Status:                    None => Need Info              

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Follow-up Comment #1:

Are you sure this is a bug?
My interpretation is that you misunderstand how Octave works.

First you make an array V.
Then you call a function f() to operate on that array.
Now you apparently think that f(V) directly operates on V in the calling
scope. But that's not the way things work in Octave:

1. When you call a function along the lines of f(V), f() operates on its
*local copy* of V, not on V itself. In other words, Octave calls functions
with arguments by value, not by reference. If inside f() you change V, it'll
create a deep copy, so memory consumption doubles. That deep copy is returned
as the output of f(V), see below.

2. Any function always returns a value. That can be a scalar, an array,
struct, anything. 
If you don't supply a return argument, Octave will put the outcome in the
default return argument, a variable called "ans".

So after calling f(V) you'll end up with two arrays:
* The original, untouched V
* ans, a copy of V with ans(1) having a value of 5

When you then clear V, obviously "ans" still exists. 
That also happens if you call octave with "eval" as the same scopes (calling
and called) will be created. 

Or, did I misunderstand you?

I'm tempted to close this bug report right now with "Invalid" but I'll await
your response.


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