Talk:Error hiding

Examples

The examples here definitely aren't Java. They looks like Delphi.

---

A real-life example of Error Hiding should be, also (C++ code):

 try
 {
   doSomething() ;
   doSomethingElse() ;
   anotherDoSomething() ;
 }
 catch(...)
 {
 }

This is the kind of code that make you want to die when you finally discover it.

The text would be : Another justification of Error Hiding is to avoid component crashing in case of failure. Despite the error, the component continues its job. The user (and the testers) never see the crash, even if some anomalies could be discovered, as the results are not those expected. As it is this code is extremely difficult to debug (and is even more in case of ested "empty try/catch" Error Hiding code), and any anomaly is extremely difficult to trace to its origin, increasing maintenance costs, only to keep up an appearance of robustness.

Another real-life, VBScript-based Error hiding:

 If doSomething() Then
   If doSomethingElse() Then
     If anotherDoSomething() Then
        anotherOtherDoSomething()
     End If
   End If
 End If

The text would be : Another implicit Error Hiding is discarding error handling altogether and using the return parameters of functions to indicate if the process succeeded (true) or not (false). The consequence is that when some error happens, it is hidden by the code (because it's error prone or simply verbose to add an Else clause) until someone notices something is amiss. A devious consequence is that when some similar code is written, but without the If/End If clauses, and is executed after the first code, the second code will fail, but no one will know the failure happened before and was hidden. Thus one can provoke the appearance of a bug months after the bug was first introduced (but hidden and thus, never discovered).

(Paercebal 16:40, 4 October 2006, GMT+1)

As no one complained/commented, added the previous examples to the Error Hiding page.

(Paercebal 15:30, 17 October 2006, GMT+1)

Links

Added link from anti-pattern. I suggest we remove the linkless template. It's a fact of life that some articles may only have one or two relevant links due to being highly specialised. Stephenbooth uk 15:54, 2 October 2006 (UTC)

The being no objections to my suggestion to remove the linkless template, I'll now remove it.--Stephenbooth uk 16:08, 8 October 2006 (UTC)

Long history.

Error hiding has been around much longer than exception-handling programming languages. It has been a problem in the C programming language since its inception, and exceptions were included in C++ to try to catch the problem (no pun intended).

There are two ways to put error hiding into a C program. One way is to generate your own error message without attempting to resolve errno:

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>

int main(int argc, char **argv)
{
   FILE *file = fopen(argv[1], "r");
   if(FILE == NULL) {
       fprintf(stderr, "%s: cannot open\n", argv[1]);
       exit(1);
   }
   /* More error-hiding code follows */
}

C code like that above is still being written today. The two ways to fix that error (under POSIX systems) are perror (which prints the error message for you) and strerror (which returns a string describing the error):

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>

int main(int argc, char** argv)
{
   FILE *file = fopen(argv[1], "r");
   if(FILE == NULL) {
#ifdef USE_PERROR
       perror(argv[1]);
#elif defined(USE_STRERROR)
       fprintf(stderr, "%s: %s\n", argv[1], strerror(errno));
#else /* Error hiding */
       fprintf(stderr, "Huh? Something's not right!\n");
#endif
       exit(1);
   }
   /* More error-hiding code follows */
}

The other way to create an error-hiding condition is by ignoring the return values of standard library functions. Programs that do this can crash just like C++ and Java programs that have empty catch blocks.

75.186.36.20 (talk) 22:39, 20 January 2008 (UTC)