On Mon, Aug 3, 2009 at 1:21 PM, Rado<rki...@gmail.com> wrote:
>
> Hello,
>
> (I apologize if this has been discussed and it is a design decision).
> I just noticed that graphs are passed by value instead of passed by
> reference (which i think is standard in python).
Graphs are pass by reference. Your function modify below does not
modify G, it overwrites it. Instead make a function like
def modify(G):
G.hello = "world"
and test again.
William
>
> example:
>
> sage:def modify(G):
> sage: G=graphs.CompleteGraph(4)
> sage:G=graphs.PetersenGraph()
> sage:modify(G)
> sage:G
> Petersen graph: Graph on 10 vertices
>
> However, a normal python behavior should be.
>
> sage:def modify_list(L):
> sage: L.append(3)
> sage:L=[1,2]
> sage:modify_list(L)
> sage:L
> [1,2,3]
>
> This can be disastrous if your are passing big graphs.
> Rado
> >
>
--
William Stein
Associate Professor of Mathematics
University of Washington
http://wstein.org
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