[R] do.call method within namespace

[Paul Roebuck]

How does one go about invoking a method within a namespaced
package if that package has not been loaded via library
method?

Given "mypackage" and method "foo" within:
    mypackage::foo(1, 2, 3)

Executing the same method's function call:
    do.call("foo", list(1, 2, 3))

didn't work. Nor did the following:
    do.call("mypackage::foo", list(1, 2, 3))

There some other means to do this without loading the
package via library method?

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SIGSIG -- signature too long (core dumped)