Verbose
Class to writing verbose messages to a connection or file
Package: R.utils
Class Verbose
Object
~~|
~~+--
Verbose
Directly known subclasses:
NullVerbose
public static class Verbose
extends Object
Class to writing verbose messages to a connection or file.
- Keywords
- classes, programming, IO
Usage
Verbose(con=stderr(), on=TRUE, threshold=0, removeFile=TRUE, core=TRUE, ...)
Arguments
- con
- A
connection
or acharacter
string filename. - on
- A
logical
indicating if the writer is on or off. - threshold
- A
numeric
threshold that thelevel
argument of any write method has to be equal to or larger than in order to the message being written. Thus, the lower the threshold is the more - removeFile
- If
TRUE
andcon
is a filename, the file is first deleted, if it exists. - core
- Internal use only.
- ...
- Not used.
Output levels
As a guideline, use the following levels when outputting verbose/debug message using the Verbose class. For a message to be shown, the output level must be greater than (not equal to) current threshold. Thus, the lower the threshold is set, the more messages will be seen.
- <= -100<="" li="">=>
A compatibility trick and a speed-up trick
If you want to include calls to Verbose in a package of yours in order
to debug code, but not use it otherwise, you might not want to load
R.utils all the time, but only for debugging.
To achieve this, the value of a reference variable to a Verbose class
is always set to TRUE
, cf. typically an Object reference has value NA
.
This makes it possible to use the reference variable as a first test
before calling Verbose methods. Example:
foo <- function(..., verbose=FALSE) {
# enter() will never be called if verbose==FALSE, thus no error.
verbose && enter(verbose, "Loading")
}
Thus, R.utils is not required for foo()
, but for
foo(verbose==Verbose(level=-1))
it is.
Moreover, if using the NullVerbose
class for ignoring all verbose
messages, the above trick will indeed speed up the code, because
the value of a NullVerbose reference variable is always FALSE
.
See Also
Examples
verbose <- Verbose(threshold=-1)
header(verbose, "A verbose writer example", padding=0)
enter(verbose, "Analysis A")
for (kk in 1:10) {
printf(verbose, "step %d
", kk)
if (kk == 4) {
cat(verbose, "Turning OFF verbose messages")
on(verbose)
} else if (kk == 6) {
off(verbose)
cat(verbose, "Turned ON verbose messages")
}
if (kk %in% c(5,8)) {
enter(verbose, "Sub analysis ", kk)
for (jj in c("i", "ii", "iii")) {
cat(verbose, "part ", jj)
}
exit(verbose)
}
}
cat(verbose, "All steps completed!")
exit(verbose)
ruler(verbose)
cat(verbose, "Demo of some other methods:")
str(verbose, c(a=1, b=2, c=3))
print(verbose, c(a=1, b=2, c=3))
summary(verbose, c(a=1, b=2, c=3))
evaluate(verbose, rnorm, n=3, mean=2, sd=3)
ruler(verbose)
newline(verbose)