do.call, browser and traceback

Did you mean that?  Both are errors.  Perhaps

f <- function(...) browser()
do.call(f, mtcars)

Sorry, yes, that is what I meant.

What is being used is

        Rprintf("Called from: ");
        PrintValueRec(cptr->call,rho);

in src/main/main.c.  We could certainly allow an option to limit the
deparse length, but I have to say that quite often the useful information
is well down the list of arguments.  There is currently no user control.

It would be nice to have some user control - I find the first 100
characters or so is usually sufficient, especially when the real
problem is further down the stack.  It is a real pain when you have
used do.call with a 10,000 row dataframe - and then it is basically
impossible to find the problem by manual inspection anyway.  Even
limiting to 1000 characters would be a big improvement.

Hadley