Question: I'm directing users to a page on my site from email (possibly an email client). When they reach the site they are presented with login screen and the address where they were headed is lost. 

How can I capture the entire address that they were trying to visit, so that I can redirect them to it once they log in?

Answer: 
basically R5 ref class does not cache the method until it is necessary. This is probably a kind of delayed evaluation.

And the caching takes place when you access the method via `$`.
So, AFAIK, there is no way to access the method via [[string]]

But you can find a workaround using .dollarForEnvRefClass like this:

```
> X <- new("Number", value = 1)
> ls(X@.xData)
[1] "value" # no methods named "addOne" before caching
> X[["addOne"]]
NULL
> methods:::.dollarForEnvRefClass(X, "addOne") # cache it
Class method definition for method addOne()
function () 
{
    value <<- value + 1
}
<environment: 0x116a4aa00>
> ls(X@.xData)
[1] "addOne" "value"  # you can find it
> X$value # value is 1
[1] 1
> X[["addOne"]]() # call the method
> X$value  # the method works
[1] 2

```

if you are interested in more detail, see the implementation:  

<http://svn.r-project.org/R/trunk/src/library/methods/R/refClass.R>

Maybe there is more straightforward way.
Report as bug on r-devel so John Chambers can fix it.