• bastien penavayre (33/33) May 07 2017 Hi something's been bugging me for a while,
• Adam D. Ruppe (6/24) May 07 2017 It isn't evaluated, it is just compiled. The compile happens
• bastien penavayre (34/36) May 07 2017 I just realized that I accidentally posted this while editing.
• Stefan Koch (3/9) May 08 2017 compile your code with the -vcg-ast switch and look at the .cg

bastien penavayre <swac31 gmail.com> writes:

Hi something's been bugging me for a while,
for the following code:

{
    auto t = tuple(0,0);
    return true;
    auto v = t[5];
    return false;
}

Why is the code following "return true" evaluated ? I know that 
it's the same
with the C++ but I was wondering why ?
My guess is for goto/labels but I find odd to evaluate it by 
default.
Furthermore one of my issues with this is that it has a negative 
impact on "static if" and make it cumbersome in some situations.

For instance this snippet comming from 
"https://github.com/uncrustify/uncrustify/issues/252"

ClLinearExpression opBinary(string op) (double constant)
{
static if (op == "+")
             return new ClLinearExpression(this, 1, constant);
         else
             static if (op == "-")
                 return new ClLinearExpression(this, 1, -constant);
             else
                 static if (op == "*")
                     return new ClLinearExpression(this, constant, 
0);
                 else
                     static if (op == "/")
                         return new ClLinearExpression(this, 1.0 / 
constant, 0);
     }

Adam D. Ruppe <destructionator gmail.com> writes:

On Sunday, 7 May 2017 at 22:34:14 UTC, bastien penavayre wrote:
 Why is the code following "return true" evaluated ?

It isn't evaluated, it is just compiled. The compile happens 
before it is run, so it doesn't really know if it is reachable 
yet.

 ClLinearExpression opBinary(string op) (double constant)
 {
 static if (op == "+")
             return new ClLinearExpression(this, 1, constant);
         else
             static if (op == "-")
                 return new ClLinearExpression(this, 1, 
 -constant);
             else
                 static if (op == "*")
                     return new ClLinearExpression(this, 
 constant, 0);
                 else
                     static if (op == "/")
                         return new ClLinearExpression(this, 1.0 
 / constant, 0);
     }

I would just write it `else static if` all on one line and not 
indent further. Then it barely looks any different anyway.

bastien penavayre <swac31 gmail.com> writes:

On Sunday, 7 May 2017 at 23:20:26 UTC, Adam D. Ruppe wrote:
 I would just write it `else static if` all on one line and not 
 indent further. Then it barely looks any different anyway.

I just realized that I accidentally posted this while editing.
I agree with you on that this is barely different from just 
adding "else".

The example that I wanted to put was the following.

{
     enum index = ...;
     static if (I >= args.length)
        return ...; //uses index
     else
     {
        enum result = ...;
        static if (!result[0])
        {
           static if (name.length == 0)
              return ...;
           else static if (result[2] >= txt.length)
              return ...;
           else
              return ...;
        }
        else
        {
           enum next = ...;
           static if (!next[0])
              return ...;
           else
           {
              ...
              return ...;
           }
        }
    }
}

Stefan Koch <uplink.coder googlemail.com> writes:

On Sunday, 7 May 2017 at 23:41:00 UTC, bastien penavayre wrote:
 On Sunday, 7 May 2017 at 23:20:26 UTC, Adam D. Ruppe wrote:
 [...]

 I just realized that I accidentally posted this while editing.
 I agree with you on that this is barely different from just 
 adding "else".

 [...]

compile your code with the -vcg-ast switch and look at the .cg 
output.