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copied!<p><strong>Edit of 2013-08-05</strong></p> <p>Using <code>sapply()</code> instead of <code>lapply()</code>, simplifies this considerably:</p> <pre><code>foo4 <- function(a=1, b=5, h='coconut') { frm <- formals(sys.function()) sapply(names(frm), get, envir=sys.frame(sys.parent(0)), simplify=FALSE) } foo4(b=0, h='mango') </code></pre> <p>This, though, without <code>sapply()</code> <strong>or</strong> <code>lapply()</code> might be the more elegant solution:</p> <pre><code>foo5 <- function(a=1, b=5, h='coconut') { modifyList(formals(sys.function()), as.list(match.call())[-1]) } foo5(b=0, h='mango') </code></pre> <hr> <p><strong>Original post (2011-11-04)</strong></p> <p>After casting about a bit, this looks to be the best solution. </p> <pre><code>foo <- function(a=1, b=5, h='coconut') { frm <- formals(foo) parms <- lapply(names(frm), get, envir=sys.frame(sys.parent(0))) names(parms) <- names(frm) return(parms) } foo(b=0, h='mango') # $a # [1] 1 # $b # [1] 0 # $h # [1] "mango" </code></pre> <p>There's some subtle stuff going on here with the way that <code>lapply</code> scopes/evaluates the calls that it constructs. The details are hidden in a call to <code>.Internal(lapply(X, FUN))</code>, but for a taste, compare these two calls:</p> <pre><code># With function matched by match.fun, search in sys.parent(0) foo2 <- function(a=1, h='coconut') { lapply(names(formals()), get, envir = sys.parent(0)) } # With anonymous function, search in sys.parent(2) foo3 <- function(a=1, h='coconut') { lapply(names(formals()), FUN = function(X) get(X, envir = sys.parent(2))) } foo4(a=0, h='mango') foo5(a=0, h='mango') </code></pre>

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