text and condition arguments are the same as those
that can be supplied via a call to browser. They can be retrieved
by the user once the browser has been entered, and provide a mechanism to
allow users to identify which breakpoint has been activated.
debug(fun, text = "", condition = NULL)
debugonce(fun, text = "", condition = NULL)
undebug(fun)
isdebugged(fun) At the debug prompt the user can enter commands or R expressions,
followed by a newline. The commands are described in the browser
topic.
To debug a function which is defined inside another function, single-step though
to the end of its definition, and then call debug on its name.
If you want to debug a function not starting at the very beginning,
use trace(..., at = *) or setBreakpoint.
Using debug is persistent, and unless debugging is turned off
the debugger will be entered on every invocation (note that if the
function is removed and replaced the debug state is not preserved).
Use debugonce to enter the debugger only the next time the
function is invoked.
In order to debug S4 methods (see Methods), you
need to use trace, typically calling browser,
e.g., as
trace("plot", browser, exit = browser, signature = c("track", "missing"))
The number of lines printed for the deparsed call when a function is
entered for debugging can be limited by setting
options(deparse.max.lines).
When debugging is enabled on a byte compiled function then the interpreted version of the function will be used until debugging is disabled.
browser, trace;
traceback to see the stack after an Error: ...
message; recover for another debugging approach.