DIP33: A standard exception hierarchy

[monarch_dodra]

On Monday, 1 April 2013 at 11:08:16 UTC, Lars T. Kyllingstad 
wrote:
> It's time to clean up this mess.
>
> http://wiki.dlang.org/DIP33

A quick comment about your "Error" section. You say:

"In general, Errors should not be caught, primarily because they 
indicate that the program logic is compromised, and that the 
program may therefore be in an invalid state from which there is 
no recovery".

It is actually much worst than that: errors bypass the entire 
exception handling mechanism, blasting through code that would 
handle destructors, and even flying through functions that are 
nothrow. They don't just indicate a "potential" invalid state, 
they actually *put* the program in an invalid state, from which 
there is no recovery.

That is the main mechanical difference between an "error" and an 
"exception", it is not just a philosophical "logic vs runtime".

--------

Under this situation, I'm wondering how the "OutOfMemory" is 
dealt with (you don't explain). The only logical explanation I 
can see is:
- It is not an exception and is not caught by "catch(Exception)".
- But it is not an error either, so does not corrupt the program 
state.
=> Goal: It is hard to catch, but you *can* recover from it.
Is this correct? Is this what we are going for?

--------

Other than that, I think it would be beneficial to clean up our 
exception architecture.