Taking from infinite forward ranges

[Andrew Edwards via Digitalmars-d-learn]

Is there a way to take a bounded rage from a infinite forward range?

Given the Fibonacci sequence:

	auto fib = recurrence!("a[n-1] + a[n-2]")(1, 1);

I can take the first n elements:

	take(fib, 10);

But say I want all positive elements below 50000 in value (there are 
eight such values [2, 8, 34, 144, 610, 2584, 10946, 46368]), how would I 
"take" them? Of course I could filter the range, leaving only positive 
values, and then take(fib, 8). But what if I didn't know there were 8, 
how could I take them from there filtered range?

Currently I do this:

	foreach(e; fib)
	{
	    if (e >= val) break;
	    // so something with e
	}

or

	while((e = fib.front()) < n)
	{
	    // do something with e
	    fib.popFront();
	}

Is there a better way?