local variable assignment: first copies from higher frame?
ah, that makes perfect sense in the functional programming sense of things. thanks! On Wed, Aug 14, 2013 at 10:19 PM, Peter Meilstrup
<peter.meilstrup at gmail.com> wrote:
Not anything that complicated -- your answer is in the R language definition under 'Subset assignment' and the part in "Function calls" that describes assignment functions. Whenever a call is found on the left side of a `<-`, it is munged by sticking a "<-" on the function name and pulling out the first argument. So my_list$x <- x which is syntactically equivalent to `$`(my_list, x) <- x is effectively transformed into something like: my_list <- `$<-`(my_list, x, x) The function `$<-` gets its argument from wherever it is found, and returns a modified version. Peter