| Exception {R.oo} | R Documentation |
Package: R.oo
Class Exception
Object
~~|
~~+--try-error
~~~~~~~|
~~~~~~~+--condition
~~~~~~~~~~~~|
~~~~~~~~~~~~+--error
~~~~~~~~~~~~~~~~~|
~~~~~~~~~~~~~~~~~+--simpleError
~~~~~~~~~~~~~~~~~~~~~~|
~~~~~~~~~~~~~~~~~~~~~~+--Exception
Directly known subclasses:
InternalErrorException, RccViolationException, RdocException
public static class Exception
extends simpleError
Creates an Exception that can be thrown and caught. The Exception
class is the root class of all other Exception classes.
Exception(..., sep="", collapse=", ")
... |
One or several strings, which will be concatenated and contain informative message about the exception. |
sep |
The string to used for concatenating several strings. |
collapse |
The string to used collapse vectors together. |
Methods:
as.character | Gets a character string representing of the Exception. | |
getCall | - | |
getLastException | Static method to get the last Exception thrown. | |
getMessage | Gets the message of the Exception. | |
getStackTrace | Gets the stack trace saved when the exception was created. | |
getStackTraceString | Gets the stack trace as a string. | |
getWhen | Gets the time when the Exception was created. | |
print | Prints the Exception. | |
printStackTrace | Prints the stack trace saved when the exception was created. | |
throw | Throws an Exception that can be caught. |
Methods inherited from error:
as.character, throw
Methods inherited from condition:
as.character, conditionCall, conditionMessage, print
Methods inherited from Object:
$, $<-, [[, [[<-, as.character, attach, attachLocally, clearCache, clone, detach, equals, extend, finalize, gc, getEnvironment, getFields, getInstantiationTime, getStaticInstance, hasField, hashCode, ll, load, objectSize, print, registerFinalizer, save
Henrik Bengtsson (http://www.braju.com/R/)
See also tryCatch() (and try()).
######################################################################
# 1. To catch a regular "error" exception thrown by e.g. stop().
######################################################################
x <- NA
y <- NA
tryCatch({
x <- log(123);
y <- log("a");
}, error = function(ex) {
print(ex);
})
print(x)
print(y)
######################################################################
# 2. Always run a "final" expression regardless or error or not.
######################################################################
filename <- tempfile("R.methodsS3.example")
con <- file(filename)
tryCatch({
open(con, "r");
}, error = function(ex) {
cat("Could not open ", filename, " for reading.\n", sep="")
}, finally = {
close(con)
cat("The id of the connection is ",
ifelse(is.null(con), "NULL", con), ".\n", sep="")
})
######################################################################
# 3. Creating your own Exception class
######################################################################
setConstructorS3("NegativeLogValueException", function(
msg="Trying to calculate the logarithm of a negative value", value=NULL) {
extend(Exception(msg=msg), "NegativeLogValueException",
.value = value
)
})
setMethodS3("as.character", "NegativeLogValueException", function(this, ...) {
paste(as.character.Exception(this), ": ", getValue(this), sep="");
})
setMethodS3("getValue", "NegativeLogValueException", function(this, ...) {
this$.value;
})
mylog <- function(x, base=exp(1)) {
if (x < 0)
throw(NegativeLogValueException(value=x))
else
log(x, base=base)
}
# Note that the order of the catch list is important:
l <- NA;
x <- 123;
tryCatch({
l <- mylog(x);
}, NegativeLogValueException = function(ex) {
cat(as.character(ex), "\n")
}, "try-error" = function(ex) {
cat("try-error: Could not calculate the logarithm of ", x, ".\n", sep="")
}, error = function(ex) {
cat("error: Could not calculate the logarithm of ", x, ".\n", sep="")
})
cat("The logarithm of ", x, " is ", l, ".\n\n", sep="")