Semantics of mixed CT and RT statements

Timoses timosesu at
Sun Dec 23 00:52:23 UTC 2018

On Saturday, 22 December 2018 at 10:29:08 UTC, NaN wrote:
> Just do
> if ((is(T == SomeType)) || (b))
> First bit will be evaluated at compile time but or-ed with 'b' 
> at runtime.
> The point is if you want the whole thing evaluated in one 
> rather than in sequence, then the whole expression is dependant 
> on a runtime variable, which makes using static if on half of 
> it wrong.

I'm not asking for "How to do this now?". I'm just communicating 
an idea and am curious about your thoughts about it.

The point is that

> if ((is(T == SomeType)) || (b))

misses the point of statically generating content IN CASE a 
condition is true at compile time.

static if (T)
     // do A
else if (b) // this already looks a bit like mixing static and 
     // do A

The intention is to only do a check of b at run-time when T is 
false. If T is true, there is no need to check anything at 
However, the above has redundant duplicate statement '// do A'.

Hence: Mixing static if and RT sounds alluring (the syntax is 
made up, but tells the story, I believe. Got a better idea?):

     static if (T) || if (b)
         // do A

The ability of D to write generic code with static statements is 
amazing already. The question is: Could it be even richer and 

The case for the following (again: made up syntax!)

     static if (T) && if (b)
         // do A

equals the very short

     static if (T) if (b)
         // do A

This thread is merely of explorative nature and does not suggest 
any concrete improvements or nags about lack of any existing 

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