So I was listening to the discussion about opApply in the "lazy" thread.
Somebody mentioned that opApply would be better if we could eliminate
the int return code.
So I thought, "well, you could make the unusual situations (return,
break, etc.) exceptions, but that would be too slow..."
Then I thought, "wouldn't it be cool if the compiler could recognize
that we had a void return value, and somehow convert the exception into
a simple return code..."
Then I thought, "what if we could delcare a function's return type to be
'exception'?"
The idea here is that if you had return type 'exception', then
exceptions coming out of that function would be returned as return
values rather than thrown with the ordinary mechanism. The calling
function would be responsible for checking that return code and handling
it properly if an exception were returned.
So, inside this type of function, "throw" statements would be converted
(by the compiler) into "return"s. And when you called a function of
this type, it would check the return code and throw the proper exception
if one was returned. In something like opApply, where you have this
type of function calling this type of delegate, the compiler-generated
code would look like opApply does now.
PROPOSED SYNTAX
exception opApply(exception delegate(ref MyType) dg)
{
<do some looping stuff>
dg(<thing>)
// compiler checks the return code for us!
}
END SYNTAX
Thoughts?
