Duration at runtime

[Zekereth via Digitalmars-d-learn]

I'm confused by the following:

import std.stdio;
import std.datetime;

void main()
{
string unitType = "seconds";
auto seconds = 1;
//	auto myDur = dur!(unitType)(seconds); // Error unitType can't 
be read at compile time.

auto myDur = dur!("seconds")(seconds); // Compiles why?
}

How is seconds able to be read at compile time but unitType 
cannot?


Thanks!

Re: Duration at runtime

[Adam D. Ruppe via Digitalmars-d-learn]

On Friday, 19 February 2016 at 04:08:02 UTC, Zekereth wrote:
How is seconds able to be read at compile time but unitType 
cannot?


"seconds" is a literal value that the compiler knows about. 
unitType is a variable that might change between its declaration 
and use (it doesn't here, but the compiler doesn't check if it 
actually does, just if it *can*), so the compiler doesn't allow 
it.

Re: Duration at runtime

[Zekereth via Digitalmars-d-learn]

On Friday, 19 February 2016 at 04:16:23 UTC, Adam D. Ruppe wrote:

On Friday, 19 February 2016 at 04:08:02 UTC, Zekereth wrote:
How is seconds able to be read at compile time but unitType 
cannot?


"seconds" is a literal value that the compiler knows about. 
unitType is a variable that might change between its 
declaration and use (it doesn't here, but the compiler doesn't 
check if it actually does, just if it *can*), so the compiler 
doesn't allow it.


Thanks a lot Adam!

So is there a way around this?. I want duration to be 
configurable at runtime.

Re: Duration at runtime

[Zekereth via Digitalmars-d-learn]

On Friday, 19 February 2016 at 04:21:43 UTC, Zekereth wrote:
On Friday, 19 February 2016 at 04:16:23 UTC, Adam D. Ruppe 
wrote:

On Friday, 19 February 2016 at 04:08:02 UTC, Zekereth wrote:
How is seconds able to be read at compile time but unitType 
cannot?


"seconds" is a literal value that the compiler knows about. 
unitType is a variable that might change between its 
declaration and use (it doesn't here, but the compiler doesn't 
check if it actually does, just if it *can*), so the compiler 
doesn't allow it.


Thanks a lot Adam!

So is there a way around this?. I want duration to be 
configurable at runtime.


Never mind I found a better solution to my problem by storing a 
Duration instead of the unitType. Works just fine.


Thanks a lot I appreciate your help!

Re: Duration at runtime

[Steven Schveighoffer via Digitalmars-d-learn]

On 2/18/16 11:36 PM, Zekereth wrote:

On Friday, 19 February 2016 at 04:21:43 UTC, Zekereth wrote:

On Friday, 19 February 2016 at 04:16:23 UTC, Adam D. Ruppe wrote:

On Friday, 19 February 2016 at 04:08:02 UTC, Zekereth wrote:

How is seconds able to be read at compile time but unitType cannot?


"seconds" is a literal value that the compiler knows about. unitType
is a variable that might change between its declaration and use (it
doesn't here, but the compiler doesn't check if it actually does,
just if it *can*), so the compiler doesn't allow it.


Thanks a lot Adam!

So is there a way around this?. I want duration to be configurable at
runtime.


Never mind I found a better solution to my problem by storing a Duration
instead of the unitType. Works just fine.

Thanks a lot I appreciate your help!


Because it might help with some future issue:

Instead of auto, declare the unitType as immutable or enum:

immutable unitType = "seconds";
enum unitType = "seconds";

Then the compiler knows it won't change.

-Steve