Dear Ross Thank you for your explanation, now mymethod works (Simon gave me already a hint).
Regarding the use of this list, I am confused. Which of my former questions regarding S4 classes belong to this list: https://stat.ethz.ch/pipermail/r-devel/2007-March/044840.html https://stat.ethz.ch/pipermail/r-devel/2007-March/044918.html https://stat.ethz.ch/pipermail/r-devel/2007-March/044937.html Since I am trying to develop a package for Bioconductor, should I use the Bioconductor development list instead? Best regards Christian Ross Boylan wrote: > On Fri, Mar 30, 2007 at 10:45:38PM +0200, cstrato wrote: > >> Dear all, >> >> Assume that I have an S4 class "MyClass" with a slot "myname", which >> is initialized to: myname="" in method("initialize"): >> myclass <- new("MyClass", myname="") >> >> Assume that class "MyClass" has a method "mymethod": >> "mymethod.MyClass" <- >> function(object, myname=character(0), ...) { >> [EMAIL PROTECTED] <- myname; >> #or: myName(object) <- myname >> } >> setMethod("mymethod", "MyClass", mymethod.MyClass); >> >> Furthermore, I have a replacement method: >> setReplaceMethod("myName", signature(object="MyClass", value="character"), >> function(object, value) { >> [EMAIL PROTECTED] <- value; >> return(object); >> } >> ) >> >> I know that it is possible to call: >> myName(myclass) <- "newname" >> >> However, I want to replace the value of slot "myname" for object "myclass" >> in method "mymethod": >> mymethod(myclass, myname="newname") >> >> Sorrowly, the above code in method "mymethod" does not work. >> >> Is there a possibility to change the value of a slot in the method of a >> class? >> > > Yes, but to make the effect persistent (visible might be a more > accurate description) that method must return the > object being updated, and you must use the return value. R uses call > by value semantics, so in the definition of mymethod.MyClass when you > change object you only change a local copy. It needs to be > "mymethod.MyClass" <- > function(object, myname=character(0), ...) { > [EMAIL PROTECTED] <- myname; > object > } > > Further, if you invoke it with > mymethod(myclass, "new name") > you will discover myclass is unchanged. You need > myclass <- mymethod(myclass, "new name") > > You might consider using the R.oo package, which probably has > semantics closer to what you're expecting. Alternately, you could > study more about R and functional programming. > > Ross Boylan > > P.S. Regarding the follow up saying that this is the wrong list, the > guide to mailing lists says of R-devel > "This list is intended for questions and discussion about code > development in R. Questions likely to prompt discussion unintelligible > to non-programmers or topics that are too technical for R-help's > audience should go to R-devel," > The question seems to fall under this description to me, though I am > not authoritative. It is true that further study would have disclosed > what is going on. Since the same thing tripped me up too, I thought > I'd share the answer. > > > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
