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digitalmars.D.learn - Why I can't catch the exception?

reply Suliman <evermind live.ru> writes:
I really can't understand why try-catch block do not handle 
exception.
digit 1 is printing, so exception is accrue after it, but why 
nothing in catch block?

http://img.ctrlv.in/img/16/06/05/57546861d8e81.png

Here is my code:

void dbSetup()
{
     try
     {
         //getcwd do not return correct path if run from task 
shoulder
         string dbpath = 
buildPath((thisExePath[0..((thisExePath.lastIndexOf("\\"))+1)]), 
dbname);
         if(!dbpath.exists)
         {
             writeln("It's seems you are runnining Application 
first time\n You should set up admin password");
             auto db = DataBase(dbname);
             writeln("1");
             auto usersCollection = db.collection!User("Users", 
true); // base on struct User
             usersCollection.put(User(0, "admin", "123", 
"admins")); // defaults
             writeln("2");
             writeln("[INFO] db with default credentials created");
         }

         else
         {
             writeln("[INFO] db exists");
             return;
         }
     }

     catch(Exception e)
     {
         writeln("Can't setup DB");
         writeln(e.msg);
     }

}

I am using https://gitlab.com/PiotrekDlang/DraftLib/
Jun 05 2016
next sibling parent reply Adam D. Ruppe <destructionator gmail.com> writes:
On Sunday, 5 June 2016 at 18:02:12 UTC, Suliman wrote:

 I really can't understand why try-catch block do not handle 
 exception.
 digit 1 is printing, so exception is accrue after it, but why 
 nothing in catch block?

 http://img.ctrlv.in/img/16/06/05/57546861d8e81.png



     catch(Exception e)



You are catching Exception, but it is throwing Error. They are 
two separate things.

You shouldn't typically catch Error, instead try to fix the bug 
it indicates. But you can if you want by catch(Error e)
Jun 05 2016
parent reply Era Scarecrow <rtcvb32 yahoo.com> writes:
On Sunday, 5 June 2016 at 18:15:47 UTC, Adam D. Ruppe wrote:

 On Sunday, 5 June 2016 at 18:02:12 UTC, Suliman wrote:

 I really can't understand why try-catch block do not handle 
 exception.
 digit 1 is printing, so exception is accrue after it, but why 
 nothing in catch block?

 http://img.ctrlv.in/img/16/06/05/57546861d8e81.png

     catch(Exception e)



 You are catching Exception, but it is throwing Error. They are 
 two separate things.

 You shouldn't typically catch Error, instead try to fix the bug 
 it indicates. But you can if you want by catch(Error e)



  The assertion is being thrown in the storage.d and backtracking 
it basically points to line 115 (usersCollection), so am going to 
guess based on error messages alone that you are passing a 
struct/class that doesn't match inputs that it is expecting for 
one of the elements it needs to store.

  So my advice is to look at the User struct/class, and then look 
at the DB's User table. But this is just a far thrown guess at 
the problem.
Jun 05 2016
parent Piotrek <piotrek unknownuniverse.net> writes:
On Sunday, 5 June 2016 at 18:20:12 UTC, Era Scarecrow wrote:

  The assertion is being thrown in the storage.d and 
 backtracking it basically points to line 115 (usersCollection), 
 so am going to guess based on error messages alone that you are 
 passing a struct/class that doesn't match inputs that it is 
 expecting for one of the elements it needs to store.

  So my advice is to look at the User struct/class, and then 
 look at the DB's User table. But this is just a far thrown 
 guess at the problem.


You are very close. This is just a limitation of the current 
database code which can only handle the simplest structs.

https://gitlab.com/PiotrekDlang/DraftLib/issues/4

Piotrek
Jun 05 2016
prev sibling parent ag0aep6g <anonymous example.com> writes:
On 06/05/2016 08:02 PM, Suliman wrote:

 I really can't understand why try-catch block do not handle exception.
 digit 1 is printing, so exception is accrue after it, but why nothing in
 catch block?

 http://img.ctrlv.in/img/16/06/05/57546861d8e81.png

 Here is my code:

 void dbSetup()
 {
      try
      {


[...]

      }

      catch(Exception e)
      {
          writeln("Can't setup DB");
          writeln(e.msg);
      }

 }


An AssertError is not an Exception (in the narrow sense) [1], but an 
Error. Both Exception and Error [2] derive from Throwable [3].

An Error signals an unrecoverable problem. You should not try to catch 
and handle them.

An AssertError in particular is thrown when an `assert` fails. In your 
case the assert is in database\storage.d, line 312. A failing assert 
signals means that there's an error in the program. A condition is not 
met that should be met at all times.

The compiler will let you catch Error and Throwable, but you really 
shouldn't do that. Instead fix your code so that it doesn't fail the assert.
Jun 05 2016