Question about exception specification

[Robert Fraser]

Graham St Jack Wrote:

> I read WalterAndrei.pdf recently, and liked most of what was in there.
> 
> However, there was the line: "Exception specifications: bad idea" on a 
> slide that discussed a possible nothrow keyword.
> 
> Can anyone explain why they are a bad idea? And if they are in fact a 
> bad idea, how do I find out what exceptions can be thrown by a function? 
> Eyeballing heaps of code doesn't count as a way!

It's been debated ad infinitum, and there are definite advantages to exception specification, especially in smaller projects. For a large project, though, the general consensus I think is that it reduces productivity considerably while not giving much significant advantage, and it encourages bad programming practices such as:

try
{
    // Do stuff
}
catch(Exception e)
{
    // ignore
}

... just to avoid exception specification, since the place you actually deal with an exception, in a very large project, could be 9 calls up th hierarchy. It also makes functors, function pointers, closures, delegates, etc. hard to implement.

As for how to determine which exceptions a function throws, that information belongs in the documentation of the function.

FWIW, I agree that for smaller projects/functions, exception specification works quite well.

As for how to determine what