| browserText {base} | R Documentation |
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
n |
The number of contexts to skip over, it must be non-negative. |
Details
Each call to browser can supply either a text string or a condition.
The functions browserText and 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.
browserSetDebug provides a mechanism for initiating the browser in
one of the calling functions. See sys.frame for a more
complete discussion of the calling stack. To use browserSetDebug
you select some calling function, determine how far back it is in the call
stack and call browserSetDebug with n set to that value.
Then, by typing 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
browserText returns the text, while browserCondition
returns the condition from the specified browser context.
browserSetDebug returns NULL, invisibly.
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.
Author(s)
R. Gentleman