Closure and lm in R -

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hi tried prepare little demo code closures in r when stumbled odd behavior. using debug realize failure happens due fact inside of lm line being executed 

mf <- eval(mf, parent.frame())

however seems defeat functional aspect of programming closures ?

what missing ? here little example 

# typical closure use  foo <- function(formula,data,weight=null) {   if(is.null(weight)) w=ones(nrow(data),1) else w=weight       force(w)     lm(formula,data,weights=w) }  setup_something <- function(...) {    function(formula,data) {      foo(formula,data,...)    } }  # set our model function model <- setup_something()  # set our data  df = data.frame(x=seq(1,10,1),y=c(1:10)^1.5 * 3 + 2) model(y~x,df)

error in eval(expr, envir, enclos) : object 'w' not found

instantiating formula (i.e.x~y) captures both environment created in, in cases happens in parent.frame() of call model().

if want subjugate environment, can explicitly adding line right before call lm(formula,data,weights=w):

# explicitly replace formula's environment current frame attr(formula,'.environment')  <-  sys.frame(sys.nframe())

or implicitly by replacing call lm(formula,data,weights=w) with:

#instantiate new forumla based on existing formula lm(stats::formula(unclass(formula)),data,weights=w)

by way of background, if stick following line lm() right before call mf <- eval(mf, parent.frame()):

print(ls(envir=parent.frame()))

you list of object names includes "w". however, 'mf' object being evaluated stats::model.frame line:

mf[[1l]] <- quote(stats::model.frame)

and stats::model.frame evaluates arguments mf in context of .environment attribute of formula.


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