Re: Blocks passed to constructors - is this behavior by design?

Marte Raphael Y. Soliza wrote:
> Notice that it doesn't print 'hello'. The break affects the caller of 
> the yield to the block. So, it returns immediately without finishing the 
> whole method. This is consistent with other methods, though I'm not sure 
> if this is intended behavior if used in the context of constructors, 
> because you are usually expecting an instance of the class when using 
> new. In any case, you can simply avoid using break for safety.

I'll put this another way, in your example:

puts Foo.new { break 42 }

The break lives within the top-level context. The semantics of break are 
that when it occurs inside a closure its result should propagate back 
out through the method that received the closure until it reaches the 
containing context again, where the break's value is then available. So 
in this case, the break travels back up through Foo#initialize, Foo::new 
(or really, Class::new in this case), and to the top-level caller, where 
42 is returned.

It's consistent with the behavior of break, but a little odd when 
considering that it's escaping a constructor/initializer. 
Recommendation: don't do that.

- Charlie