Dear Christian
this post from Martin Morgan on class versioning in Bioconductor's
Biobase package might be relevant:
https://stat.ethz.ch/pipermail/bioc-devel/2006-May/000545.html
and also section 6 of this:
http://www.bioconductor.org/packages/2.4/bioc/vignettes/Biobase/inst/doc/BiobaseDevelopment.pdf
Best wishes
Wolfgang
----------------------------------------------------
Wolfgang Huber EMBL-EBI http://www.ebi.ac.uk/huber
cstrato wrote:
Dear all,
Since my package is based on S4 classes, I would like to know how to add
a slot to an existing S4 class without breaking the code of users of my
package.
Assume the following S4 class:
setClass("MyClass",
representation(name = "character",
type = "character",
data = "data.frame"
),
prototype(name = "",
type = "Default",
data = data.frame(matrix(nr=0,nc=0))
)
)#MyClass
Assume that a user has created an object:
> myclass <- new("MyClass", name="MyName", type="MyType", data=tmp)
> str(myclass)
Now I would like to add another slot "info" to MyClass:
setClass("MyClass",
representation(name = "character",
type = "character",
data = "data.frame",
info = "data.frame"
),
prototype(name = "",
type = "Default",
data = data.frame(matrix(nr=0,nc=0)),
info = data.frame(matrix(nr=0,nc=0))
)
)#MyClass
Now when the user loads my package with S4 class MyClass containing a
new slot and calls:
> str(myclass)
Error in FUN(c("name", "type", "data", "info")[[4L]], ...) :
no slot of name "info" for this object of class "MyClass"
>
My question is:
Is there any possibility or special trick, which would avoid this error
message?
Are there other possibilities to access an additional data.frame from an
existing class?
Is there something like an "evolution" of S4 classes, which
distinguishes the different implementations of an S4 class, and allows
the user to keep the object of an old class?
Best regards
Christian
_._._._._._._._._._._._._._._._._._
C.h.r.i.s.t.i.a.n S.t.r.a.t.o.w.a
V.i.e.n.n.a A.u.s.t.r.i.a
e.m.a.i.l: cstrato at aon.at
_._._._._._._._._._._._._._._._._._
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