If Statement with Declaration

[Jerry via Digitalmars-d]

On Friday, 4 November 2016 at 14:16:44 UTC, Matthias Bentrup 
wrote:
> On Thursday, 3 November 2016 at 22:29:34 UTC, Jerry wrote:
>>     if(int i = someFunc(); i >= 0)
>>     {
>>         // use i
>>     }
>> Thoughts on this sort of feature?
>
> I would prefer the syntax
>
>   if( (int i = someFunc()) >= 0 )
>   {
>     // use i
>   }
>
> as this matches the already existing assignment expression 
> syntax if you pull the declaration out of the if expression.

Well you can argue the "if( init ; condition )" syntax matches 
"for( init ; condition ; update)", minus the "update" section. 
It's cleaner as well as you don't need an extra set of 
parenthesizes. As well that sort of syntax would allow multiple 
declaration. Which I'm not sure that's desired, it becomes 
increasingly messy.

if((int i = someFunc()) >= 0 && (int j = otherFunc()) >= 0)
{
}

You also can't use the declaration as input for someFunc():

     if(int i; someFunc(&i) >= 0)
     {
     }