What's missing to make D2 feature complete?

[via Digitalmars-d]

On Wednesday, 24 December 2014 at 09:02:56 UTC, Kagamin wrote:
> On Wednesday, 24 December 2014 at 08:39:26 UTC, Ola Fosheim 
> Grøstad wrote:
>> int myfunc(int n){
>>    ...lotsofstuff...
>>    x = mayormaynotchange(n);
>>   ...lotsofstuff...
>>   return n>0 ? x : 0;  // modified from "return x"
>> }
>
> If you require another variable for a sanitized version of `n`, 
> you get confused, when to use `n` and when to use `x`, they are 
> almost the same and if you pick a wrong value, the code will 
> break sometimes.

Not really, because you should strive to keep mutable state 
local. Validation does not belong to the implementation, so "the 
right way" is to put it in a wrapper before you call the function 
that does the actual work.

When functions get long and complicated and evolve over time then 
all mutable state become a source for errors.

I never want to change parameter values for long functions. I do 
it for because I am in a hurry. The more constraint the language 
impose the better code I am likely to write.