"Roger D. Peng" <[EMAIL PROTECTED]> writes: > I've encountered a (I think) related problem when using promises to load > relatively large datasets. For example something like > > delayedAssign("x", getBigDataset()) > > runs into the same problem if you hit Ctrl-C while 'x' is being evaluated for > the first time. Afterwards, there's no way to retrieve the dataset > associated > with 'x'. > > Active bindings work in this case, but the problem is that I usually only > want > to load a large dataset once.
You can do that with active bindings. Have the function look in an environment for the data. If found, return it. If not, load it into the env and then return it. We are using this approach in the BSGenome package in BioC (look there for an example if you want) and it provides behavior very similar to lazy data, but more manageable in a number of ways. + seth ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel