There is no benefit. It is a rather cumbersome approach to checking whether something behaves as you expect it to. `as.data.frame` will force it into what you need; if it cannot be forced, then it will fail. That it can be converted to a data.frame is the class' designers responsibility, not yours. So you can use `as.data.frame` on *any* input that you need to behave as a data.frame. Consider a grouped tribble; now you have to test 2 different classes.
Kindly, Stefan Stefan McKinnon Høj-Edwards ph.d. Genetics +44 (0)776 231 2464 +45 2888 6598 Skype: stefan_edwards 2017-09-26 11:15 GMT+01:00 Gábor Csárdi <csardi.ga...@gmail.com>: > What is the benefit here, compared to just calling as.data.frame() on it? > > Gabor > > On Tue, Sep 26, 2017 at 11:11 AM, Daniel Lüdecke <d.luede...@uke.de> > wrote: > > Since tibbles add their class attributes first, you could use: > > > > tb <- tibble(a = 5) > > inherits(tb, "data.frame", which = TRUE) == 1 > > > > if "tb" is a data frame (only), TRUE is returned, for tibble FALSE. You > could then coerce to data frame: as.data.frame(tb) > > > > -----Ursprüngliche Nachricht----- > > Von: R-package-devel [mailto:r-package-devel-boun...@r-project.org] Im > Auftrag von Göran Broström > > Gesendet: Dienstag, 26. September 2017 12:09 > > An: r-package-devel@r-project.org > > Betreff: Re: [R-pkg-devel] tibbles are not data frames > > > > > > > > On 2017-09-26 11:56, Gábor Csárdi wrote: > >> On Tue, Sep 26, 2017 at 10:35 AM, Joris Meys <joris.m...@ugent.be> > wrote: > >>> I don't like the dropping of dimensions either. That doesn't change > >>> the fact that a tibble reacts different from a data.frame. So tibbles > >>> do not inherit correctly from the class data.frame, and it can thus > >>> be argued that it's against OOP paradigms to pretend tibbles inherit > >>> from the class data.frame. > >> > >> I have yet to see an OOP system in which a subclass cannot override > >> the methods of its superclass. Not only is this in line with OOP > >> paradigms, it is actually one of the essential OOP features. > >> > >> To be more constructive, if you have a function that only works with > >> data frame inputs, then it is good practice to check that the supplied > >> input is indeed a data frame. This is independent of tibbles. > > > > It is not. I check input for being a data frame, but tibbles pass that > test. That's the essence of the problem. > > > >> In practice it seems to me that an easy fix is to just call > >> as.data.frame on the input. This should either convert it to a data > >> frame, or throw an error. > > > > Sure, but I still need to rewrite the package. > > > > Görn > > > >> For tibbles it > >> drops the tbl* classes. > >> > >> Gabor > >> > >>> Defensive coding techniques would check if it's a tibble and return > >>> an error saying a data.frame is expected. Unless tibbles inherit > >>> correctly from data.frame. > >>> > >>> I have nothing against tibbles. But calling them "data.frame" raises > >>> expectations that can't be fulfilled. > >> > >> [...] > >> > >> ______________________________________________ > >> R-package-devel@r-project.org mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-package-devel > >> > > > > ______________________________________________ > > R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/ > listinfo/r-package-devel > > > > -- > > > > _____________________________________________________________________ > > > > Universitätsklinikum Hamburg-Eppendorf; Körperschaft des öffentlichen > Rechts; Gerichtsstand: Hamburg | www.uke.de > > Vorstandsmitglieder: Prof. Dr. Burkhard Göke (Vorsitzender), Prof. Dr. > Dr. Uwe Koch-Gromus, Joachim Prölß, Martina Saurin (komm.) > > _____________________________________________________________________ > > > > SAVE PAPER - THINK BEFORE PRINTING > > ______________________________________________ > > R-package-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-package-devel > > ______________________________________________ > R-package-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-package-devel > [[alternative HTML version deleted]] ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel
