Multiple Exception Sub Classes With CodeIgniter

[eluser]Aken[/eluser]
Various options:

1) Include them in /application/config/constants.php
2) Extend the Exceptions class by creating a file at /application/core/MY_Exceptions.php, and define them in that file along with the extended Exceptions class (which wouldn't have anything in it unless you wanted to add something specific).
3) Add them to index.php, or have index.php include/require a file that has them defined.

There isn't a specific use case for this that is "standard CI way". But CI is just PHP, so use native PHP in whatever way is convenient for you.