Detect packages needed by S4 classes

[HenrikBengtsson]

> library(bigmemory)
> X <- as.big.matrix(matrix(1:10, nrow = 2L))
> class(X)
[1] "big.matrix"
attr(,"package")
[1] "bigmemory"

In other words, if X is a global, we should append:

packages <- c(packages, attr(class(X), "package"))

[HenrikBengtsson]

A core R example:

> def <- methods::getClass("MethodDefinition")

> base::isS4(def)
[1] TRUE

> class(def)
[1] "classRepresentation"
attr(,"package")
[1] "methods"

Since isS4() is defined in base, we can do something like:

x <- globals[[1]]
if (isS4(x)) packages <- c(packages, attr(class(x), "package"))

without adding a dependency on methods.

[HenrikBengtsson]

Use the 'stats4' for testing; it's a 'base' package

[HenrikBengtsson]

This might bring to the globals package, i.e. packagesOf.Globals