How Nested Functions Work, part 2

[Walter Bright]

Jeremie Pelletier wrote:
> Those new and better ways of doing things in programming languages might 
> imply semantics some programmers are not willing to use, and would 
> rather keep their older language and implement their own version of that 
> feature themselves, pure C will always dominate in that in my opinion 
> since I can't think of anything in the language itself that generate 
> calls to runtime methods,

There are several things that do - things like floating point 
conversions, long division, etc.

> which fortunately can also be done in D. A lot 
> of D features require runtime calls, not everyone is willing to dig into 
> the runtime to learn what such calls imply in terms of performance. For 
> example, I myself stay off scope() for real time code because I'm aware 
> it needs to call into _d_framehandler.

That's only called when handling an exception, not for just setting up 
the frame and normally executing it. Also, if you annotate your 
functions as "nothrow", and your guarded statements do not throw, the 
compiler will elide the exception handling code.