IIRC it has to do with the environment where the assignment takes place. Take a look at the language specs for details: http://cran.r-project.org/doc/manuals/R-

IIRC it has to do with the environment where the assignment takes place. Take a look at the language specs for details: http://cran.r-project.org/doc/manuals/R-lang.html http://cran.r-project.org/doc/manuals/R-lang.html especially: http://cran.r-project.org/doc/manuals/R-lang.html#Argument-evaluation http://cran.r-project.org/doc/manuals/R-lang.html#Argument-e...