On 02/03/2016 11:39 PM, Andrea Fontana wrote:
> On Wednesday, 3 February 2016 at 17:49:39 UTC, Marc Schütz wrote:
>> On Wednesday, 3 February 2016 at 16:07:59 UTC, Messenger wrote:
>>> What is a good way to try to force it? Using enum? Then optionally
>>> copying the value once to avoid the "manifest constant" copy/paste
>>> behaviour, where applicable?
>>
>> template forceCTFE(alias expr) {
>>     alias forceCTFE = expr;
>> }
>>
>> auto value = forceCTFE!(some_expression());
>
> Interesting :)
> Thank you!

I would use enum forceCTFE(alias expr)=expr; though. With alias it won't force compile-time evaluation of expressions that can be interpreted as symbols.

On Wednesday, 3 February 2016 at 22:45:47 UTC, Timon Gehr wrote:
> I would use enum forceCTFE(alias expr)=expr; though. With alias it won't force compile-time evaluation of expressions that can be interpreted as symbols.

I've a code that build a JSON object using a wrapper over std.json.

This code:

----

enum forceCTFE(alias expr)=expr;

auto j = forceCTFE!(
  JSOB
  (
    "hello", JSOB("world", 3),
    "arr", JSAB("hello", JSOB("world", 1))
  )
);

j.put("/hello/world", "!");
j.put("/hello/blah", 42);	
// Here j == {"arr":["hello",{"world":1}],"hello":{"blah":42,"world":"!"}}
----

shows a 10% performance gain over this:

----

auto j = JSOB
(
  "hello", JSOB("world", 3),
  "arr", JSAB("hello", JSOB("world", 1))
);

j.put("/hello/world", "!");
j.put("/hello/blah", 42);	

----

(inside a loop).

And it's just a small json in this case.
That's pretty good IMHO :)

On Friday, 5 February 2016 at 09:36:37 UTC, Andrea Fontana wrote:
> On Wednesday, 3 February 2016 at 22:45:47 UTC, Timon Gehr wrote:
>> I would use enum forceCTFE(alias expr)=expr; though. With alias it won't force compile-time evaluation of expressions that can be interpreted as symbols.
>
> I've a code that build a JSON object using a wrapper over std.json.
>
> This code:
>
> ----
>
> enum forceCTFE(alias expr)=expr;
>
> auto j = forceCTFE!(
>   JSOB
>   (
>     "hello", JSOB("world", 3),
>     "arr", JSAB("hello", JSOB("world", 1))
>   )
> );
>
> j.put("/hello/world", "!");
> j.put("/hello/blah", 42);	
> // Here j == {"arr":["hello",{"world":1}],"hello":{"blah":42,"world":"!"}}


Reading/parsing a JSON or a XML using std.json / std.xml could be done on CTFE ?

On Friday, 5 February 2016 at 09:49:38 UTC, Luis wrote:
> Reading/parsing a JSON or a XML using std.json / std.xml could be done on CTFE ?

parseJSON() from std.json doesn't work with CTFE.

But I can build objects with with my code that works over std.json.
So if you convert (with mixins)

{ "hello" : "world" }
to
JSOB("hello", "world)

You can parse it ar compile time. :)