Re: foo_cs = foo{:} - feature or bug ? (octave-3.4.2); also, sizeof(foo{:})

[Ben Abbott]

On Aug 9, 2011, at 1:27 AM, Sergei Steshenko wrote:

> "
> octave:3> foo_cs = foo{:}
> foo_cs =  1
> "
> 
> part looks like a (awkward) way of taking/making a value out of a list,
> that is why I expect 'sizeof' to work on that value - because it _does_
> work on '1 + 2' expression.

I agree. It is an awkward and confusing way to assign a value. I'd avoid using 
such syntax.

My impression is that you understand what cs-lists, are and how they work. But 
just in case, below, there is a brief description of how cs-lists are used in 
Octave. Let me know if there is some part that isn't clear.


The term <cs-list> is short hand for _comma_separated_list_of_objects_.
If an octave session has objects A, B, and C, then a <cs-list> of these objects 
would be "A, B, C".

<cs-lists> are used by the m-file language as inputs to functions, "fun 
(<cs-list>)", and as outputs to functions, "[<cs-list>] = fun (<cs-list>)".

<cs-lists> are also used when creating objects.  An object, with an array of 
values, is created by enclosing a <cs-list> in square brackes, "A = [1, 2, 3]". 
In this case the <cs-list> is "1, 2, 3".

An array of objects is created by enclosing a <cs-list> in curly brackets, "B = 
{pi, true, 'foobar'}".  In this case the <cs-list> is "pi, true, 'foobar'".  
Arrays of objects are refered to a cells, and are objects themselves.

Using Octave's parser, <cs-lists> may be produced from either cell or structure 
objects. If "B" is a cell object, a <cs-list> is produced by "B{m:n}" or just 
"B{:}". If "S" is a structure, a <cs-list> is produced by "S(m:n).field", or 
just "S(:).field".


Ben