Question

How can I make sure that after I “catch” an error and log it no further code steps are executed (I do not want to use q())?

My usage scenario is like this:
– do some calculations
– if error occurs log it
– stop executing any further steps in the code

I tried to solve this using code example below (print is used instead of true logging function):

handleMySimpleError<-function(e, text) {
    # Let's log the error
    print(paste0(text, ": ", e))
    # This should stop execution of any further steps but it doesn't
    stop("Now, stop. For real.")
}

print("Starting execution...")
tryCatch(
    stop("My simple error."),
    error=function(e) {handleMySimpleError(e, "could not finish due to")}, finnaly=NULL
)
print("Successfully ended execution...")

I somehow hoped that print(“Successfully ended execution…”) would never get executed… But, here is the output I get:

> handleMySimpleError<-function(e, text) {
+   # Let's log the error
+   print(paste0(text, ": ", e))
+   # This should stop execution of any further steps but it doesn't
+   stop("Now, stop. For real.")
+ }
>  
> print("Starting execution...")
[1] "Starting execution..."
> tryCatch(
+   stop("My simple error."),
+   error=function(e) {handleMySimpleError(e, "could not finish due to")}, finnaly=NULL
+ )
[1] "could not finish due to: Error in doTryCatch(return(expr), name, parentenv, handler): My simple error.\n"
Error in handleMySimpleError(e, "could not finish due to") : 
Now, stop. For real.
> print("Successfully ended execution...")
[1] "Successfully ended execution..."

How to prevent from print(“Successfully ended execution…”) being executed? What is the correct strategy to stop code processing after error is logged in error handler function?

Answer 1

Just wrap curly braces around it

>     {
+       handleMySimpleError<-function(e, text) {
+           # Let's log the error
+           print(paste0(text, ": ", e))
+           # This should stop execution of any further steps but it doesn't
+           stop("Now, stop. For real.")
+       }
+       print("Starting execution...")
+       tryCatch(
+           stop("My simple error."),
+           error=function(e) {handleMySimpleError(e, "could not finish due to")}, finally=NULL
+       )
+       print("Successfully ended execution...") 
+     }
[1] "Starting execution..."
[1] "could not finish due to: Error in doTryCatch(return(expr), name, parentenv, handler): My simple error.\n"
Error in handleMySimpleError(e, "could not finish due to") : 
  Now, stop. For real.