What is the exact meaning of 'nothrow'?

[ZombineDev via Digitalmars-d-learn]

On Thursday, 11 June 2015 at 00:06:24 UTC, Yuxuan Shui wrote:
> I want to know exactly what is considered to be 'throw'.
>
> I'm able to use dynamic arrays (which can throw 'Range 
> violation') and asserts in a nothrow function. Shouldn't those 
> be considered 'throw'?

In D there are two types of exceptions: logic errors (derived 
from 'Error') and environment exceptions (derived from 
'Exception').

Logic errors are considered to be irrecoverable (eg. your program 
should be terminated because people generally don't write code to 
handle them - no one wraps their array accesses in try {...} 
catch {...})

Environment exceptions are stuff like user input and network and 
file access. This are problems that you generally want to handle 
and that's why they're considered recoverable.

So 'Exception's propagate through function calls and 'Error's 
terminate the program immediately.

A function 'f' marked as "nothrow" indicates that no exceptions 
shall escape from it (if a function that 'f' calls can throw, 'f' 
must written, so that it catches the exception), but since 
'Error's terminate the program immediately the callers of 'f' 
should not care about them and that's why 'Error's don't brake 
the 'nothrow' promise of 'f'.