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new_function
Create a function
Description
This constructs a new function given its three components: list of arguments, body code and parent environment.
Usage
new_function(args, body, env = caller_env())
Arguments
args |
A named list or pairlist of default arguments. Note
that if you want arguments that don't have defaults, you'll need
to use the special function |
body |
A language object representing the code inside the
function. Usually this will be most easily generated with
|
env |
The parent environment of the function, defaults to the
calling environment of |
Examples
f <- function() letters g <- new_function(NULL, quote(letters)) identical(f, g) # Pass a list or pairlist of named arguments to create a function # with parameters. The name becomes the parameter name and the # argument the default value for this parameter: new_function(list(x = 10), quote(x)) new_function(pairlist2(x = 10), quote(x)) # Use `exprs()` to create quoted defaults. Compare: new_function(pairlist2(x = 5 + 5), quote(x)) new_function(exprs(x = 5 + 5), quote(x)) # Pass empty arguments to omit defaults. `list()` doesn't allow # empty arguments but `pairlist2()` does: new_function(pairlist2(x = , y = 5 + 5), quote(x + y)) new_function(exprs(x = , y = 5 + 5), quote(x + y))