On Tue, Jan 20, 2015 at 2:22 PM, Juan Manuel Truppia <[email protected]> wrote:
> Let's follow an example. I'm developing my own package. I add data.table > to imports in my description file. This means I have to use the :: operator > each time I want to call a data.table function. Can I use := in this setup? > "I have to use / Can I use" - here you refer to the user using your package or yourself as the developer trying to use data.table functions and := from within your package? > > On Tue, Jan 20, 2015, 10:01 Arunkumar Srinivasan <[email protected]> > wrote: > >> Juan, >> >>> >>> I already know that. >>> >> Okay, great. >> >>> I usually struggle when using data.table inside my own packages. I start >>> by listing it in imports only (and not importing anything) >>> >> "imports only (and not importing anything)"? - what do you mean? >> >>> but end up depending on it, as for the users to be able to manipulate >>> the data.tables with [ and :=. >>> >> It depends on whether you want the data.table NAMESPACE to be attached or >> not. I think these posts may help: >> >> http://r.789695.n4.nabble.com/Re-R-CMD-check-checking-in-development-version-of-R-td4696125.html#none >> >> http://stackoverflow.com/questions/8637993/better-explanation-of-when-to-use-imports-depends >> >> >>> I end up importing some or all of data.table also, because I don't know >>> how to call := the :: notation. >>> >> I don't really follow this. Why do you want to use `::` along with `:=`. >> The last post we just discussed that it can't be done, as it is not >> designed to be used outside of `[...]` and in very specific ways. Check >> data.table:::`:=`. It is designed to error. This post might help: >> http://stackoverflow.com/q/7033106/559784 >> >>> My specific problem was on using := during on.Load. >>> >> It'd be useful to know what you are trying to do, along with your code. >> >>> I already know how to use it, and know that it can only be used inside [. >>> Maybe it is imperative to @import data.table to be able to use :=? >>> >> I don't follow exactly how you are trying to use := to answer this. >> >> Arun >> >>> >>> On Mon, Jan 19, 2015, 19:35 Arunkumar Srinivasan <[email protected]> >>> wrote: >>> >>>> Within the square brackets in "DT[ .... ]" and even there, only in `j` >>>> (as the error message points out). >>>> >>>> On Mon, Jan 19, 2015 at 11:31 PM, Juan Manuel Truppia < >>>> [email protected]> wrote: >>>> >>>>> Arun, what does "within the frame of data.table" mean? >>>>> >>>>> On Mon, Jan 19, 2015, 19:17 Arunkumar Srinivasan < >>>>> [email protected]> wrote: >>>>> >>>>>> Juan, >>>>>> >>>>>> `:=` is designed to be used only within the frame of data.table. >>>>>> >>>>>> On Mon, Jan 19, 2015 at 10:45 PM, Juan Manuel Truppia < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> Hi, I'm using data.table inside my own packages. I'm having some >>>>>>> trouble using data.table functions on my .onLoad method. >>>>>>> I'm actually depending (not importing) data.table, but even then, I >>>>>>> can't get := to work in .onLoad. >>>>>>> I'm using the `:=`(a = x, b = y) version, and getting >>>>>>> >>>>>>> Error in `:=`(a = x) : >>>>>>> Check that is.data.table(DT) == TRUE. Otherwise, := and `:=`(...) >>>>>>> are defined for use in j, once only and in particular ways. See >>>>>>> help(":="). >>>>>>> >>>>>>> If I comment that, and then run it from the console after the >>>>>>> package is loaded, it works. >>>>>>> >>>>>>> Any ideas? >>>>>>> >>>>>>> _______________________________________________ >>>>>>> datatable-help mailing list >>>>>>> [email protected] >>>>>>> >>>>>>> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help >>>>>>> >>>>>> >>>>>> >>>>
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