I have been trying to write a "proper" print method for a package, and
have
almost gotten what I want. From a reading of the relevant section in R
Extensions and the introduction to methods, I've stuck the whole business
into a character object and used:
NextMethod("print")
However, instead of not printing quotes and displaying the usual
representation of the string, I get the whole string, newlines and all, in
quotes. My attempt to shamelessly copy someone else's print method
was foiled as most of them don't display when one types the function name. I
presume this is a feature of namespaces.
Needless to say, searching the archives for "print & method"
retrieved a
cornucopia of useless information. I wonder if anyone would be kind enough to
inform me where to look for the proper incantation? Thanks.
RedHat EL3 L:inux
R-1.9.1
Last.Drink - Aurora Expresso
Jim
If a method is hidden in a namespace, use getAnywhere(print.whatever) to see the code. -roger Jim Lemon wrote:> I have been trying to write a "proper" print method for a package, and have > almost gotten what I want. From a reading of the relevant section in R > Extensions and the introduction to methods, I've stuck the whole business > into a character object and used: > > NextMethod("print") > > However, instead of not printing quotes and displaying the usual > representation of the string, I get the whole string, newlines and all, in > quotes. My attempt to shamelessly copy someone else's print method > was foiled as most of them don't display when one types the function name. I > presume this is a feature of namespaces. > > Needless to say, searching the archives for "print & method" retrieved a > cornucopia of useless information. I wonder if anyone would be kind enough to > inform me where to look for the proper incantation? Thanks. > > RedHat EL3 L:inux > R-1.9.1 > Last.Drink - Aurora Expresso > > Jim > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html >
Jim Lemon wrote:> I have been trying to write a "proper" print method for a package, and have > almost gotten what I want. From a reading of the relevant section in R > Extensions and the introduction to methods, I've stuck the whole business > into a character object and used: > > NextMethod("print")Well, it depends. If you have some inheritance of classes, you may reallay want to use NextMethod(), but that's not necessary if you want to write your own print method print.myclass() to print stuff that is not from any superclass.... Check out how to write methods in, e.g., Venables and Ripley (2000): "S Programming", Springer. Uwe Ligges> However, instead of not printing quotes and displaying the usual > representation of the string, I get the whole string, newlines and all, in > quotes. My attempt to shamelessly copy someone else's print method > was foiled as most of them don't display when one types the function name. I > presume this is a feature of namespaces. > > Needless to say, searching the archives for "print & method" retrieved a > cornucopia of useless information. I wonder if anyone would be kind enough to > inform me where to look for the proper incantation? Thanks. > > RedHat EL3 L:inux > R-1.9.1 > Last.Drink - Aurora Expresso > > Jim > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
Jim, As Uwe said, that's not what NextMethod() is for. I suspect what you really want is simply cat()ing the object that you created in your print() method. If you look in must print() and summary() methods, you'll see a lot of cat(). HTH, Andy> From: Uwe Ligges > > Jim Lemon wrote: > > > I have been trying to write a "proper" print method for a > package, and have > > almost gotten what I want. From a reading of the relevant > section in R > > Extensions and the introduction to methods, I've stuck the > whole business > > into a character object and used: > > > > NextMethod("print") > > Well, it depends. > If you have some inheritance of classes, you may reallay want to use > NextMethod(), but that's not necessary if you want to write your own > print method print.myclass() to print stuff that is not from any > superclass.... > Check out how to write methods in, e.g., Venables and Ripley > (2000): "S > Programming", Springer. > > Uwe Ligges > > > > > However, instead of not printing quotes and displaying the usual > > representation of the string, I get the whole string, > newlines and all, in > > quotes. My attempt to shamelessly copy someone else's print method > > was foiled as most of them don't display when one types the > function name. I > > presume this is a feature of namespaces. > > > > Needless to say, searching the archives for "print & > method" retrieved a > > cornucopia of useless information. I wonder if anyone would > be kind enough to > > inform me where to look for the proper incantation? Thanks. > > > > RedHat EL3 L:inux > > R-1.9.1 > > Last.Drink - Aurora Expresso > > > > Jim > > > > ______________________________________________ > > R-help at stat.math.ethz.ch mailing list > > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > >
Thank you all, gentlemen. getAnywhere(), which I blush to say I have seen flash by in a few recent messages, allowed me to see the awful truth. But for the fact that it sounds like one of those gizmos in science fiction that allow one to turn up in the next galaxy, I might have twigged. Jim