What is the best way to stop App after exception?

[Ali Çehreli via Digitalmars-d-learn]

On 02/15/2016 03:38 AM, Suliman wrote:
 > I have got class Config with method parseconfig. I need terminate App if
 > parsing of config was failed. The problem that I do not know how to do
 > it better.

As others said, exceptions inherited from Error indicate situations 
where the application cannot continue.

However, a function like parseconfig() does not sound like it would know 
whether the error that it detected is serious enough to terminate the 
whole application. It is conceivable that the caller can simply say 
"next file" and continue. So, I think parseconfig() should either 
propagate or throw an Exception and let the caller decide.

 > void parseconfig()
 > {
 >   try
 >   {
 >    //something go wrong
 >   }
 >
 > catch(Exception e)
 >   {

The way I see it, exceptions should be caught only if there is anything 
to be done with that error condition.

 >    writeln(e.msg);
 >    // throw any exception here

Needing to catch an exception just to log and then rethrow it is 
something that is against the whole spirit of exceptions mechanisms. It 
brings exceptions back to using error codes: Every function must do the 
same to leave behind a trail, presumably for debugging.

There are other options:

- Log before the error condition at a different logging level.

- Put a break point at the constructor of the exception. The back trace 
will show the backtrace.

- Automate the last two and call a library like libunwind and dump the 
backtrace from the constructor of exception. (However, you may not want 
to log every thrown exception.)

I know that sometimes the thrown exception does not carry enough 
information. Then it's ok to do what you're doing: catch and throw 
another exception.

 >   }
 > }
 >
 >
 > But my main.d also have try catch block and parseconfig() calls inside
 > it. The problem that wen exception rise I do not know how to terminate
 > app. Exception simply print on screen and app is continue.

I don't know how that happens. I am presuming you do throw another 
exception where you say

    // throw any exception here

Then all you need to do is catch in main, log the problem and return 
non-zero from main.

 > void main()
 >   {
 >   try
 >    {
 >     parseconfig(); // exception was already handled inside:

But it did rethrow, right? Then it should be fine.

 >  void
 > parseconfig()
 >    }
 >   }
 >
 > What is the best practice to stop app?

Ali