similar to: inconsistencies between ?class and ?UseMethod

hi,usRs,i am studing the R programming,but i can not get the point abut the difference between UseMethod and NextMehod.i have read the manual and try to find the solutin from internet,but i still not master it well.so anyone can give me a guide?it will be better to show some examples . thank you !

(opening new bug report thread, on suggestion of BDR ..) I said on vaguely related topic: MM> There's another long-standing MM> UseMethod / NextMethod / Dispatch problem that I've never traced/solved.. MM> MM> Look at the $RHOME/tests/mode-methods.R file ! Peter Dalgaard already remarked : PD> ..i.e. this: PD> abc <- function(x, ...) { PD> if

>> One clear moral seems to be don't do anything more inside a >> generic function than you really need to do. Keep it *very* >> simple indeed. >> > I recall JMC saying something like, all generic functions > should be one line long; a call to the appropriate UseMethod. It certainly is encouraging to know that others also have been confused by aspects of

My question is when the object argument of NexthMethod be used? In the following example, weather object argument is used will not affects the result. ### foo=function(x) {UseMethod("foo")} foo.cls1=function(x) { x=x+1;class(x)<-"ncls" NextMethod() } foo.ncls=function(x) { cat("ncls\n") } foo.cls2=function(x) { cat("cls2\n");print(x) }

Hi, although I've done S3 dispatching for more than a decade now, I think I managed to overlook/avoid the following pitfall when using NextMethod(): If you explicitly pass argument '...' to NextMethod(), you will effectively pass those argument twice to the "next" method! EXAMPLE: foo0 <- function(...) UseMethod("foo0"); foo1 <- function(...)

Hello,   ###  I created two classes "A" and "B". "A" is the superclass of "B".   setClass("A", representation(s1="numeric"),prototype=prototype(s1=8)) setClass("B",contains="A",representation(s2="character"),prototype=list(s2="hi")) myA=new("A") myB=new("B")   ####  I created

Hi all, I'd like to ask if the following behavior is a bug. To me it certainly feels surprising, at the very least. In this example, I would like to call NextMethod() from my `child` object, have `cols` be left untouched, and then substitute(cols) in the parent method. It works when you use a `parent` object (as expected), but I would have also expected to get `mpg` back when calling it from

I have another problem with NextMethod. Not sure if its related to the last problem. In this example, we have a generic called ff with methods for AsIs and test classes. We call the generic with an object of AsIs class. The corresponding method adds 1 to it and then changes the class to test followed by issuing a NextMethod. However, that results in this error (using R 2.0.0, 2004-10-04

On Sat, 18 May 2019 at 23:34, Pavel Krivitsky <pavel at uow.edu.au> wrote: > > > The issue here is that you are registering a non-standard name > > (.gen.formula) for that generic and then defining what would be the > > standard name (gen.formula) for... what purpose? IMHO, this is a bad > > practice and should be avoided. > > The situation initially arose

S Programming by Venables and Ripley (page 78) has the example listed at the end of this email. However, I get the following error when I try the example. I don't understand the descriptions of NextMethod on its help page. Could somebody let me know how to fix the error of this example? > test(x) c1 c2 Error in NextMethod() : no method to invoke Calls: test -> test.c1 -> NextMethod

Dear R developers, I will ask a very straightforward question concerning UseMethod's future, because people depending on my code wonder what will happen to it next. In R v2.0.1 NEWS it says o The undocumented use of UseMethod() with no argument is now formally deprecated. and in the R v2.0.1 help(UseMethod) it says 'UseMethod' accepts a call with no arguments and tries to

match the argument 'x' if there is another argument with prefix 'x' Full_Name: Henrik Bengtsson Version: 1.3.1 OS: Sun Solaris 8 Submission from: (NULL) (130.235.3.49) I ran into a strange problem with UseMethod(). Run the following code: foo.Bar <- function(this, x=0, xidx=0) { cat("In foo.Bar(): ", this, ", x=", x, ", xidx=", xidx,

If I do > example(lm) ... > mycoef <- function(object, ...) UseMethod("coef", object) > mycoef(lm.D9) Error in mycoef(lm.D9) : no applicable method for "coef" which is pretty surprising, as coef has a default method. After a bit of digging, this comes from do_usemethod having defenv = environment where the generic was defined */ defenv =

Dear, I'm looking for some examples on OO programming in R. I have the programming manual with explanation on UseMethod and NextMethod but I miss some practical examples to get me going (I hope). I searched the web but could not find a good independent tutorial on this. Any suggestions are welcome, Kris -- ------------------------------------------------------------------------

UseMethod has since the beginning had the 'feature' that local variables in the generic are added to the environment in which the method body is evaluated. This is documented in ?UseMethod and R-lang.texi, but use of this 'feature' has been explicitly discouraged in R-lang.texi for many years. This is an unfortunate design decision for a number of reasons (see below), so the plan

tl;dr: S3 lookup no longer works in custom non-namespace environments as of R 3.6.1. Is this a bug? I am implementing S3 dispatch for generic methods in environments that are not packages. I am trying to emulate the R package namespace mechanism by having a ?namespace? environment that defines generics and methods, but only exposes the generics themselves, not the methods. To make S3 lookup work

On Tue, 14 May 2019 at 12:31, Pavel Krivitsky <pavel at uow.edu.au> wrote: > > > Note that disabling name-based dispatch implies two things: 1) the > > inability to override your method by defining gen.formula in the > > global environment, and 2) another package can break yours (i.e., > > internal calls to gen()) by registering an S3 method for gen() after >

Yes, thanks for following up on thread here. And thanks again for clearing things up, your email was a finger snap of clarity on the whole issue. I'll add that actually it was data.table's code at fault on the storage conversion -- note that if you use an arbitrary sub-class 'foo' with no methods defined, it'll stay integer. That's because [<- calls as.Date and then

Debugging this issue: https://github.com/Rdatatable/data.table/issues/2008 We have custom class 'IDate' which inherits from 'Date' (it just forces integer storage for efficiency, hence, I). The concatenation done by rbind, however, breaks this and returns a double: library(data.table) DF = data.frame(date = as.IDate(Sys.Date())) storage.mode(rbind(DF, DF)$date) # [1]

Full_Name: Mike Kay Version: R-patched OS: Linux Submission from: (NULL) (137.75.70.37) Hi, The following patch cleans up some grammar in the docs for UseMethod (library/base/help/UseMethod) -mike --- UseMethod 2005-09-28 20:06:39.000000000 +0000 +++ /tmp/UseMethod 2005-10-31 21:21:05.534708720 +0000 @@ -5,7 +5,7 @@ Description: R possesses a simple generic function mechanism