问子类和父类不在同一文件中导致R错误

EN

mEdit <- setRefClass("mEdit",
                     fields = list( data = "matrix",
                                    edits = "list")
                     )



mEdit$methods(
    initialize = function(data=matrix()) {
        .self$data = data
    }
    )

mv <- setRefClass("matrixViewer",
                  fields = c("viewerDevice", "viewerFile"),
                  contains = "mEdit",
                  )

mv$methods( initialize =
                function(file = "./matrixView.pdf", ...) {
                    viewerFile <<- file
                    pdf(viewerFile)
                    viewerDevice <<- dev.cur()
                    dev.set(dev.prev())
                    callSuper(...)
                },
            finalize = function() {
                dev.off(viewerDevice)
            })

Loading testRefClass
Error in getClass(what, where = where) (from mv.R#1) : “mEdit” is not a defined class