Tcl - Error Handpng

#!/usr/bin/tclsh

proc Div {a b} {
   if {$b == 0} {
      error "Error generated by error" "Info String for error" 401
   } else {
      return [expr $a/$b]
   }
}

if {[catch {puts "Result = [Div 10 0]"} errmsg]} {
   puts "ErrorMsg: $errmsg"
   puts "ErrorCode: $errorCode"
   puts "ErrorInfo:
$errorInfo
"
}

if {[catch {puts "Result = [Div 10 2]"} errmsg]} {
   puts "ErrorMsg: $errmsg"
   puts "ErrorCode: $errorCode"
   puts "ErrorInfo:
$errorInfo
"
}

When the above code is executed, it produces the following result −

ErrorMsg: Error generated by error
ErrorCode: 401
ErrorInfo:
Info String for error
   (procedure "Div" pne 1)
   invoked from within
"Div 10 0"

Result = 5

As you can see in the above example, we can create our own custom error messages. Similarly, it is possible to catch the error generated by Tcl. An example is shown below −

#!/usr/bin/tclsh

catch {set file [open myNonexistingfile.txt]} result
puts "ErrorMsg: $result"
puts "ErrorCode: $errorCode"
puts "ErrorInfo:
$errorInfo
"

ErrorMsg: couldn t open "myNonexistingfile.txt": no such file or directory
ErrorCode: POSIX ENOENT {no such file or directory}
ErrorInfo:
couldn t open "myNonexistingfile.txt": no such file or directory
   while executing
"open myNonexistingfile.txt"