ops, my bad ... and i thought i knew python :) Rado
On Aug 3, 4:04 pm, Kwankyu <ekwan...@gmail.com> wrote: > On Aug 4, 5:21 am, 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). > > > 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 > > Graphs are nothing special. Try the following: > > def modify(G): > G.delete_vertex(0) > G=graphs.PetersenGraph() > modify(G) > G > > In your example, you assign a different object to G, thus losing the > original reference. --~--~---------~--~----~------------~-------~--~----~ To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
