Hidden argument kind antipattern

[Robert Jacques]

On Tue, 19 Apr 2011 19:47:57 -0400, Vladimir Panteleev  
<vladimir at thecybershadow.net> wrote:

> On Wed, 20 Apr 2011 02:43:50 +0300, bearophile  
> <bearophileHUGS at lycos.com> wrote:
>
>> I agree. In my opinion the problem is not you using in your module a  
>> language feature designed for that very purpose. What's in question is  
>> the syntax of that language feature. I don't mind lazy arguments, but  
>> it can be argued that's better for them to require a "lazy" prefix at  
>> the calling point too. This little syntax problem that was already  
>> raised during the D2 design phase.
>
> I would like to clarify my point:
>
> Inarguably (IMO), the original intention of lazy parameters was to allow  
> passing expressions to functions that were evaluated only when required.
>
> David's library evaluates these expressions *in different threads*!
>
> Generally, I would count that any usage of "lazy" counts as abuse except  
> for evaluating the argument, at most once, during the function's  
> execution.
>

Lazy is also good at abstracting error handling. For example, I use lazy  
to perform smart C error code checking, which allows me to handle certain  
common errors and then re-try the function.