Hi Martin,
Thanks very much for your help.
>
> Hi Iago --
>
> Here's my attempt at an answer.
>
> "Iago Mosqueira (Cefas)" <[EMAIL PROTECTED]> writes:
>
> > 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
>
> You're trying to create a class in the package name space, and the
> name space is locked (cannot be modified) after the package is
> loaded. If your intention is programmatically generate static classes
> (in a kind of macro-like way) then I think you could still use this
> approach but ensure that the classes are created when the package is
> loaded (e.g., by including a class creation function that is actually
> evaluated, not just defined, in your package code).
Yes, I have tried that. Inmediatly after the creator function is defined I use
it to create a new class. And this class is exported in the package NAMESPACE.
Still, it says the package environment is locked, although the call to setClass
is part of the package.
> > This does not happen if I redefine the creator function in
> my working
> > environment.
>
> yes, here you are creating the class in the global environment, which
> is not locked (!).
>
> > 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?
>
> I think that setMethod works because the methods package has already
> created an environment within the appropriate name space (try 'ls(<pkg
> name space>, all=TRUE)' and look at the '.__<etc>' bindings). What
> setMethod does is modfies this environment, rather than the
> environment of the name space.
Thanks very for this clarification.
> Hope that helps, and is not too misleading.
Not all, very helpful. Cheers,
Iago
> Martin
>
> > 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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> >
> > ______________________________________________ R-devel@r-project.org
> > mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
>
> --
> Martin Morgan
> Bioconductor / Computational Biology
> http://bioconductor.org
>
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