Hello, > > Is there a way to force a call-by-value instead of a call-by-address? > Yes, there is one way, just do nothing. R always uses call-by-value. I'm not completely sure about this, but when you create f() the parameter x default value is a promise, not an actual, evaluated value. Courtesy lazy evaluation. It's only when you need it that it's evaluated.
For instance, using your code, you don't need to create tmp before creating f(). Since R is not evaluating tmp, there's no error to throw. You'll only get an error if you try to *use* f() without creating tmp or without a default value override. rm(f, tmp) # just to be sure f <- as.function(alist(y=, x=tmp, y + x)) f(1) # error f(1, 3) # no error tmp <- 2 f(1) # 3 Hope this helps, Rui Barradas jackl wrote > > Hi, > > i have a question regarding the as.function functionality. > I need to save multiple functions with adjusted parameters in a list. > The adjusted parameters are changed via variables in a loop. > The problem I'm facing right now is that the functions saved in > the list don't have the values of the parameters but the variable > parameter > itself. Is there a way to force a call-by-value instead of a > call-by-address? > > Example(not the real function): > tmp <- 4 > f <- as.function(alist(y=,x=tmp,y+x) > f(1) > 5 > tmp <- 2 > f(1) > 3 > > thanks ahead and sorry if this question has already been asked before. > I could not really grasp the problem to one Subject. > -- View this message in context: http://r.789695.n4.nabble.com/as-function-parameters-tp4620390p4621903.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
