trycatch
Evaluates an expression with the possibility to catch exceptions (DEPRECATED)
This function is deprecated. Use tryCatch()
instead.
Evaluates an expression with the possibility to catch exceptions.
The class of the exception thrown by a standard stop() call is
try-error. Since it contains a dash, the name must be specfied
within quotation marks. Alternatively, the name ANY can be use
to catch any exception. See examples below.
Note that the order which the catch-expressions are specify is important.
For instance, an ANY catch at the beginning will catch all exception
even if one specify other classes afterwards.
Usage
trycatch(expr, ..., finally=NULL, envir=parent.frame())Arguments
- expr
- The
expressionto be evaluated. - ...
- A catch list of named
expressions. The expression with the same name as the class of theExceptionthrown when evaluatingexpr - finally
- An
expressionthat is guaranteed to be called even if the expression generates an exception. - envir
- The
environmentin which the caught expression is to be evaluated.
Details
To make trycatch() for other exception classes than
try-error, the functions try() and stop()
had to undergo minor(!) modification. However, they are fully
compatible with the try() and
stop() in the base package.
To make exceptions to be thrown in the catch expression, e.g. in
finally or ANY, such exceptions should extend
(inherit from) the class try-error, which is for instance the
case with all stop() and throw() generated exceptions.
Currently, from R v1.8.0 there is a new implementation of trycatch(),
which is a "wrapper" around the new tryCatch() function.
If running R v1.7.1 or before the old trycatch() is used for
backward compatibility.
Value
- Returns the value of the last
expressionevaluated.
See Also
From R v1.8.0 the tryCatch() method is available;
see conditions.
For more information about exceptions see Exception.
There is also throw(), stop(), try().
Examples
For a complete example see help(Exception).