try/catch idiom in std.datetime

[growler]

On Friday, 22 November 2013 at 01:49:11 UTC, Shammah Chancellor 
wrote:
> On 2013-11-18 06:32:46 +0000, Andrei Alexandrescu said:
>> 
>> 1. Fix scope(failure) and then use it.
>> 
>> Andrei
>
> Huh?  Scope failure has no purpose here.  It does not CATCH the 
> exception and prevent it from bubbling up the call chain.    
> Try/catch does do this.
>
> -Shammah

It does if you return from the scope(failure) block. The problem 
is you cannot mark the function as "nothrow"

For example:
---
void throwingFunction() {
     throw new Exception("damn!");
}

void someFunc() // nothrow
{
     scope(failure) {
         writeln("Failed in someFunc()");
         return;
     }
     throwingFunction();
}

void main() {
     try {
         someFunc();
         writeln("Yay, someFunc() is nothrow");
     } catch(Exception e) {
         writeln("An exception in main!");
     }
}

Output:

Failed in someFunc()
Yay, someFunc() is nothrow.
---

But you cannot mark someFunc() as nothrow.