Hello,
I would like to create a function that gets passed a class name and then calls
setClass, and a few other functions, inside. I have done this in the past with
setmethod, creating accessors for all slots in a set of S4 classes. But
setClass is choking when my function is called isnide a package, telling about
an error in exists(cname, where). I assume this to be a problem with the
environment where the class is created. If I define my creator function in a
package and load it, when I call it I get
Error in assign(mname, def, where): cannot add bindings to a locked environment
This does not happen if I redefine the creator function in my working
environment.
I have attached an example of the kind of function below, and I am using R
2.5.0.
Where should I look for information on undertanding what might be going on
here? Why does this way of working succeeds with setMethod but not setClass?
The intention here is to provide an easy way for creating extended classes that
will inherit from a class already defined, instead of array as in the example.
Many thanks,
Iago
defineClass <- function(name, dimnames) {
# dim, names[2], dimnames[2]
if(names(dimnames)[1] != 'iter')
dimnames <- c(list(iter=1), dimnames)
dim <- unlist(lapply(dimnames, length))
# validity
foo <- "validity <- function(object) {"
# foo <- c(foo, "browser()")
foo <- c(foo, paste("if(all(names(dimnames(object)) != c('",
paste(names(dimnames), collapse="','", sep=""), "')))", sep=""))
foo <- c(foo, "stop(paste('dimnames are not correct for class', name))")
foo <- c(foo, "return(TRUE)}")
eval(parse(text=foo))
# setClass
setClass(name, representation('array'),
prototype=prototype(array(as.numeric(NA), dim=dim, dimnames=dimnames),
units='NA'),
validity=validity, where=sys.parent(n=-2))
# setValidity
setValidity(name, validity)
# constructors
eval(parse(text=paste("setGeneric('", name,
"', function(object, ...) standardGeneric('", name, "'))",
sep="")))
setMethod(name, signature(object='ANY'),
function(object, ...)
return(FLPar(object, ..., class=name))
)
setMethod(name, signature(object='missing'),
function(...) {
return(FLPar(..., class=name))
}
)
}
---
Iago Mosqueira
Systems Modelling
Cefas
Pakefield Rd.
Lowestoft NR33 0HT
U.K.
Tel +44 (0) 1502 558003
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