Private default function arguments

[BCS]

Hello bearophile,

> My recursive functions sometimes need to keep a bit of state, for
> example an integer that keeps the current "depth" of a tree structure
> that I'm creating or scanning, normally in D I can define the function
> like this:
> 
> /// Always use depth=0 at the first call
> 
> int foo1(int x, int depth=0) {
> 
> ...
> 
> foo1(x, depth + 1);
> 
> ...
> 
> }
> 
> The last argument depth must be zero when the function is not called
> by itself, but I must rely on convention and code comments, 

My method of choice is:

private int foo1(int x, int depth) { ... }
int foo1(int x) {return foo1(x,0); }

Good inlining might even make this exactly the same as your proposal.