On Oct 17, 12:35 pm, Florian Weimer <f...@deneb.enyo.de> wrote: > * Chris Torek: > > > In article <87y69xbz6h....@mid.deneb.enyo.de> > > Florian Weimer <f...@deneb.enyo.de> wrote: > >>Are there libraries which implement some form of spreadsheet-style > >>dependency tracking? The idea is to enable incremental updates to > >>some fairly convoluted computation. I hope that a general dependency > >>tracking framework would avoid making the computation even more > >>convoluted and difficult to change. > > > Don't know of any libraries myself, but I wrote some code to do > > topological sort for dependencies, which I can paste here. It > > is also worth noting that a lot of spreadsheets cheat: they just > > repeat a sheet-wide computation until values stop changing (or a > > cycle count limit runs out). > > I think most of the relevant implementations use dependency > information to speed up incremental recomputation. For instance, > gnumeric seems to have code for this. This is the part I'm most > interested in. I already have got an explicit ordering of the > computations (fortunately, that part is fairly simple).
And note that the repeating sheet-wide computation is a feature not a "cheat" (the default should still be to report cycles). Allowing calculations to complete even in the presence of cycles can be very useful. Michael Foord -- http://www.voidspace.org.uk/ -- http://mail.python.org/mailman/listinfo/python-list
