[R] Methods dispatch and inheritance R.oo

[Henrik Bengtsson]

Hi,

if you instead do:

setConstructorS3("ClassB", function(B=15) {
  extend(ClassA(), "ClassB",
    .size2 = B
  );
})

then you'll get:

> objB <- ClassB();
> objB
[1] "Class B: 15"


What was wrong with your setup?
What you ended up doing was to "extend" an object of class 'character'
(with value "ClassA").  With above fix, you now extend an object of
class 'ClassA' (which in turn extend 'Object').

Hope this help

/Henrik

On Wed, Nov 5, 2008 at 2:18 AM, Yuri Volchik <yuri.volchik at gmail.com> wrote:
>
> Hi to all members, i have a question about class inheritance and methods
> using R.oo package:
> I have the following code and it doesn't work, guess i'm doing smth wrong
> and there is nothing in the help.
>
> library(R.oo)
>
> setConstructorS3("ClassA", function(A=15) {
>  extend(Object(), "ClassA",
>    .size = A
>  );
> })
>
>
> setMethodS3("print", "ClassA", function(this,...) {
>  print(paste('Class A:',this$.size));
> })
>
>
> objA<-ClassA();
> objA
>
> [1] "Class A: 15"
>
> setConstructorS3("ClassB", function(B=15) {
>  extend("ClassA", "ClassB",
>    .size2 = B
>  );
> })
>
>
> setMethodS3("print", "ClassB", function(this,...) {
>  print(paste('Class B:',this$.size2));
> })
>
>
> objB<-ClassB();
> objB
>
> Error in this$.size2 : $ operator is invalid for atomic vectors
>
>
> --
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> Sent from the R help mailing list archive at Nabble.com.
>
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