Lazy eval

[Walter Bright]

Frank Benoit wrote:
> For example i have a container with a add( element ) method. Now this
> method is implemented with lazy-eval, if the container is already full,
> the argument is not evaluated.
> Or the get( index ) method does not eval the arg if the container is
> empty. And every time I have not only to remember the method name and
> arguments, now I have to know details of the implementation.
> Great, that was the silly thing they wanted to take away from me with
> this OOP ;)
> 
> Solution: Force the user the make {} around a delegate argument.
> 
> Now I get a compiler error when writing container.get(i++); Then I know,
> this is a delegate, take care with the increment, writing
> container.get({i}); i++;

While I understand your concern, I don't think the examples illustrate 
it. If a get() is done for an element that doesn't exist, the usual way 
to deal with it is throw an exception, and have some complex scheme to 
try and undo the side effects from evaluating the argument. With lazy 
evaluation, no need to undo the side effects, as only if the get() is 
guaranteed to succeed will the argument be evaluated.

The problem with requiring the { } around the argument is that 
programmers just don't like it. I don't think I can make them like it.