for() with 4 arguments to allow postcondition

[Michel Colman]

> Isn't this what a do-while loop is for, or am I missing 
> something?

Well, yes, but then you don't need the regular "for" loop either. 
After all, isn't that what a "while" loop is for?

The big advantage of "for" is that you can see at a glance what 
the initialisation, condition(s) and increments are. It describes 
the whole loop in one statement. That's the only reason why it 
was invented in the first place, because the language technically 
does not need it. You can even declare the variable right there 
so its scope is limited to the loop. With a do-while, you first 
initialize the variable before the loop (outside of it), then add 
the increment just before the end (many pages later, perhaps), 
and the condition at the very end. It's all over the place.

> foreach(i; 0..10)

I know my simple example would be optimized, and can indeed be 
written with a foreach as well. But if you use some custom class 
as the variable, or a pointer, it won't be. For example, turn i 
into a Bigint. Or for an entirely different example:

for (Display * d = firstDisplay; d != 0; d = nextDisplay)

if you have already established that at least one display is 
present.

Or even simpler:

for (int i = 1; i <= 0x10000000; i <<= 1)

I bet this won't be optimized on many compilers.

And all it would take is one extra semicolon:

for (Display * d = firstDisplay; ; d != 0; d = nextDisplay)
for (int i = 1; ; i <= 0x10000000; i <<= 1)

to tell the compiler to skip the condition before the first 
iteration.

> for(initializer;;increment){
>   if(!condition1) break;
>    body;
>    if(!condition2) break;
>}

Yes, that's exactly what I meant.

Michel