Segment violation (was Re: Why I could not cast string to int?)

[Artur Skawina]

On 02/03/12 00:20, Jonathan M Davis wrote:
> in is pointless on value types. All it does is make the function parameter 
> const, which really doesn't do much for you, and in some instances, is really 
> annoying. Personally, I see no point in using in unless the parameter is a 
> reference type, and even then, it's often a bad idea with reference types, 
> because in is really const scope, and the scope is problematic if you want to 
> return anything from that variable. It's particularly problematic with arrays, 
> since it's frequently desirable to return slices of them, and scope (and 
> therefore in) would prevent that. It's useful in some instances (particularly 
> with delegates), but I'd use in _very_ sparingly. It's almost always more 
> trouble than it's worth IMHO.

BTW, scope should have been the default for *all* reference type function
arguments, with an explicit modifier, say "esc", required to let the thing
escape. It's an all-or-nothing thing, just like immutable strings - not using
it everywhere is painful, but once you switch everything over you get the
benefits.

If it isn't obvious why - GC. The compiler can optimize the cases where it
knows a newly allocated object can't escape and reduce or omit the GC overhead.
And yes, it can also do this automatically - but that requires analyzing the
whole call chain, which is a) not always possible and b) much more expensive.

artur