capture.output function in R

Once I was wondering how to return string from function str().  I guess capture.output is one way:

capture.output              package:utils              R Documentation

Send Output to a Character String or File

Description:

     Evaluates its arguments with the output being returned as a

     character string or sent to a file.  Related to 'sink' in the same

     way that 'with' is related to 'attach'.

Usage:

     capture.output(..., file = NULL, append = FALSE)

Arguments:

     ...: Expressions to be evaluated.