| % File src/library/base/man/browserText.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2011 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{browserText} |
| \alias{browserText} |
| \alias{browserCondition} |
| \alias{browserSetDebug} |
| \title{ |
| Functions to Retrieve Values Supplied by Calls to the Browser |
| } |
| \description{ |
| A call to browser can provide context by supplying either a text |
| argument or a condition argument. These functions can be used to |
| retrieve either of these arguments. |
| } |
| \usage{ |
| browserText(n = 1) |
| browserCondition(n = 1) |
| browserSetDebug(n = 1) |
| } |
| \arguments{ |
| \item{n}{The number of contexts to skip over, it must be non-negative.} |
| } |
| \details{ |
| Each call to \code{browser} can supply either a text string or a condition. |
| The functions \code{browserText} and \code{browserCondition} provide ways |
| to retrieve those values. Since there can be multiple browser contexts |
| active at any time we also support retrieving values from the different |
| contexts. The innermost (most recently initiated) browser context is |
| numbered 1: other contexts are numbered sequentially. |
| |
| \code{browserSetDebug} provides a mechanism for initiating the browser in |
| one of the calling functions. See \code{\link{sys.frame}} for a more |
| complete discussion of the calling stack. To use \code{browserSetDebug} |
| you select some calling function, determine how far back it is in the call |
| stack and call \code{browserSetDebug} with \code{n} set to that value. |
| Then, by typing \code{c} at the browser prompt you will cause evaluation |
| to continue, and provided there are no intervening calls to browser or |
| other interrupts, control will halt again once evaluation has returned to |
| the closure specified. This is similar to the up functionality in gdb |
| or the "step out" functionality in other debuggers. |
| } |
| \value{ |
| \code{browserText} returns the text, while \code{browserCondition} |
| returns the condition from the specified browser context. |
| |
| \code{browserSetDebug} returns NULL, invisibly. |
| } |
| \author{ |
| R. Gentleman |
| } |
| \note{ |
| It may be of interest to allow for querying further up the set of browser |
| contexts and this functionality may be added at a later date. |
| } |
| |
| \seealso{ |
| \code{\link{browser}} |
| } |
| \keyword{debugging} |