Yet another const problem...

[Mehrdad]

struct Foo
{
	@property bool empty() const { return p == null; }
	@property auto front() inout { return p; }
	void popFront() { p--; }


	// So far so good? okay, let's define save()..

	auto save() inout { return typeof(this)(this.tupleof); }


	// Now let's implement opApply() using the above ^^

	int opApply(void delegate(size_t, typeof(p)) dg) const
	{
		size_t i = 0;
		int r = 0;

		// So far so good...
		for (auto me = this.save(); !r && !me.empty; me.popFront())
		{
			// Whoops, won't work -- 'me' is const! :(
			r = dg(me);
		}

		return r;
	}
}



How do you fix this without duplicating your code?