• Greatsam4sure (9/9) Jul 21 2018 auto arithmetic(T, V, U)(T a, V b, U op){
• rikki cattermole (11/23) Jul 21 2018 Simple, it was never requested to be reached.

Greatsam4sure <greatsam4sure gmail.com> writes:

auto arithmetic(T, V, U)(T a,  V b,  U op){
    return mixin("a"~op~"b");
}

//call like this
arithmetic(1.5,2.5,"op");


Compiler says the variable op is not reach at compile time.  So 
how can the varible a and b be reach at compile time and op is 
not reach. I will appreciate any help. I have also use a static 
if but the same complain.  Just a newbie in D

rikki cattermole <rikki cattermole.co.nz> writes:

On 22/07/2018 12:15 AM, Greatsam4sure wrote:
 auto arithmetic(T, V, U)(T a,  V b,  U op){
     return mixin("a"~op~"b");
 }
 
 //call like this
 arithmetic(1.5,2.5,"op");
 
 
 Compiler says the variable op is not reach at compile time.  So how can 
 the varible a and b be reach at compile time and op is not reach. I will 
 appreciate any help. I have also use a static if but the same complain.  
 Just a newbie in D

Simple, it was never requested to be reached.

The correct code is:

auto arithmetic(string op, T, V)(T a, V b) {
	return mixin("a" ~ op ~ "b");
}

arithmetic!("op")(1.5, 2.5);

D is not dynamic, if you need access to compile time features like 
string mixin, you must pass them via the template parameters. You can't 
use regular old variables to do this, as the code hasn't even been 
generated yet.