Dear List,
just out of pure curiosity: is it possible to define a function via
'substitute()' such that the function's formal arguments are specified
by a "wildcard" that is substituted when the expression is evaluated?
Simple example:
x.args <- formals("data.frame")
x.body <- expression(
out <- myArg + 100,
return(out)
)
expr <- substitute(
myFoo <- function(
ARGS,
myArg
){
print("hello world!")
print(ARGS)
eval(BODY)
},
list(ARGS=x.args, BODY=x.body)
)
eval(expr)
myFoo(myArg=5)
# works
myFoo(a=1:3, stringsAsFactors=FALSE, myArg=5)
# does not work
It works for wildcard 'BODY' in the function's body, but not for
wildcard 'ARGS' in the argument definition part of the function definition.
I thought that when writing a function that depends on some other
function like 'data.frame()', it would maybe be possible not to
'hardcode' the formal arguments of 'data.frame()' in the new function
def but to have it mapped somewhat dynamically so that when
'data.frame()' changes, the new function would change as well. This is
probably a bad idea for countless reasons, nevertheless I'd be
interested in learning if it's possible at all ;-)
TIA,
Janko
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