expressing functions

Perhaps what should be added to the previous answers is
that you can find out where the real work is done like
this:

require(ctest)
t.test
methods(t.test)
ctest:::t.test.default
ctest:::t.test.formula

If the class of the first argument to t.test is formula
then t.test.formula gets invoked so that's where the
real work is done; otherwise, t.test.default
gets invoked so that's where the real work is done.

---

# Why does expressing one function

require(ctest)
t.test

# return only

function (x, ...)
UseMethod("t.test")
<environment: namespace:ctest>

# but expressing another function

shapiro.test

# returns more complete code?

function (x)
{
DNAME <- deparse(substitute(x))
x <- sort(x[complete.cases(x)])
n <- length(x)
if (n < 3 || n > 5000)
stop("sample size must be between 3 and 5000")