fun: A compact way to define a function.

In crowding/vadr: Macros, metaprogramming, and pleasant programming idioms.

Description

fun captures its first argument unevaluated and turns it into a function. Every name used in the expression becomes an argument, unless it looks like a function call. If you don't intend to capture a particular variable, you can not provide it, and it will use a default value that pulls from the enclosing scope.

Usage

fun(expr, .all.names=FALSE)

Arguments

expr	The expression to use as the function's body.
.all.names	Whether to include call heads as parameters.

Details

"..." is supported in the function definitions and should behave as you expect.

Value

A newly constructed function.

Note

Since it doesn't know which symbols you intend to be arguments and which you intend to take from the enclosing environment, it captures all symbols in defaults; therefore it won't work as a closure that reflects changes in the enclosing environment.

Author(s)

Peter Meilstrup

Examples

f <- fun(x/y)
f(10,2)  # prints 5
f
# function (x = eval(quote(x),..fun_envir),
#           y = eval(quote(y),..fun_envir) {
#   x/y
# }

crowding/vadr documentation built on May 14, 2019, 11:33 a.m.