debug                  package:base                  R Documentation

Debug a function

Description:

     Set or unset the debugging flag on a function.

Usage:

     debug(fun)
     undebug(fun)

Arguments:

     fun: any interpreted R function.

Details:

     When a function flagged for debugging is entered, normal execution
     is suspended and the body of function is executed one statement at
     a time. A new browser context is initiated for each step (and the
     previous one destroyed). Currently you can only debug functions
     that have bodies enclosed in braces. This is a bug and will be
     fixed soon. You take the next step by typing carriage return, `n'
     or `next'. You can see the values of variables by typing their
     names. Typing `c' or `cont' causes the debugger to continue to the
     end of the function. You can `debug' new functions before you step
     in to them from inside the debugger. Typing `Q' quits the current
     execution and returns you to the top-level prompt. Typing `where'
     causes the debugger to print out the current stack trace (all
     functions that are active). If you have variables with names that
     are identical to the controls (eg. `c' or `n' ) then you need to
     use `print(c)' and `print(n)' to evaluate them.

See Also:

     `browser', `traceback' to see the stack after an `Error: ...'
     message.

