So i want bitfields for just a little bit. but i dont want its dependencies. How is it done. I have tried this. but it doesnt seem to work on gdc. :(

struct Color_t {
	static if(__ctfe){
		import std.bitmanip:bitfields;
	}
	mixin(bitfields!(
		uint, "R",    8,
		uint, "G",   8,
		uint, "B",    8,
		uint, "A", 8));
}

On Thursday, 10 March 2016 at 04:07:54 UTC, Taylor Hillegeist wrote:
> So i want bitfields for just a little bit. but i dont want its dependencies. How is it done. I have tried this. but it doesnt seem to work on gdc. :(
>
> struct Color_t {
> 	static if(__ctfe){
> 		import std.bitmanip:bitfields;
> 	}
> 	mixin(bitfields!(
> 		uint, "R",    8,
> 		uint, "G",   8,
> 		uint, "B",    8,
> 		uint, "A", 8));
> }

__ctfe is a runtime construct, not compile-time. It cannot be used with static if. More over, it's only available *inside* a function that is currently being executed in a compile-time context. It has no role outside of that.

What problem are you trying to solve here? I mean, what is the problem with whatever dependencies std.bitmanip:bitfields has that makes you only want to import it during compilation?

On Thursday, 10 March 2016 at 04:56:52 UTC, Mike Parker wrote:
> On Thursday, 10 March 2016 at 04:07:54 UTC, Taylor Hillegeist wrote:
>> So i want bitfields for just a little bit. but i dont want its dependencies. How is it done. I have tried this. but it doesnt seem to work on gdc. :(
>>
>> struct Color_t {
>> 	static if(__ctfe){
>> 		import std.bitmanip:bitfields;
>> 	}
>> 	mixin(bitfields!(
>> 		uint, "R",    8,
>> 		uint, "G",   8,
>> 		uint, "B",    8,
>> 		uint, "A", 8));
>> }
>
> __ctfe is a runtime construct, not compile-time. It cannot be used with static if. More over, it's only available *inside* a function that is currently being executed in a compile-time context. It has no role outside of that.
>
> What problem are you trying to solve here? I mean, what is the problem with whatever dependencies std.bitmanip:bitfields has that makes you only want to import it during compilation?

I am running on a MKL25Z development board. The output of the mixin works fine. but the dependencies of the std.bitmanip:bitfields are quite extensive. including std.format..etc

On Thursday, 10 March 2016 at 04:56:52 UTC, Mike Parker wrote:
> On Thursday, 10 March 2016 at 04:07:54 UTC, Taylor Hillegeist wrote:
>> So i want bitfields for just a little bit. but i dont want its dependencies. How is it done. I have tried this. but it doesnt seem to work on gdc. :(
>>
>> struct Color_t {
>> 	static if(__ctfe){
>> 		import std.bitmanip:bitfields;
>> 	}
>> 	mixin(bitfields!(
>> 		uint, "R",    8,
>> 		uint, "G",   8,
>> 		uint, "B",    8,
>> 		uint, "A", 8));
>> }
>
> __ctfe is a runtime construct, not compile-time. It cannot be used with static if. More over, it's only available *inside* a function that is currently being executed in a compile-time context. It has no role outside of that.
>
> What problem are you trying to solve here? I mean, what is the problem with whatever dependencies std.bitmanip:bitfields has that makes you only want to import it during compilation?

I feel like this should do what i want it too. but it doesn't.

struct Color_t {
	static if(1==1){
		import std.bitmanip:bitfields;
		immutable string item = bitfields!(		
				uint, "R",    8,
				uint, "G",   8,
				uint, "B",    8,
				uint, "A", 8);
	}
	mixin(item);
}

On Thursday, 10 March 2016 at 16:20:42 UTC, Taylor Hillegeist wrote:
> I feel like this should do what i want it too. but it doesn't.
>
> struct Color_t {
> 	static if(1==1){
> 		import std.bitmanip:bitfields;
> 		immutable string item = bitfields!(		
> 				uint, "R",    8,
> 				uint, "G",   8,
> 				uint, "B",    8,
> 				uint, "A", 8);
> 	}
> 	mixin(item);
> }

I wonder if compiler is smart enaugh to undestand that dependency is not needed at runtime in this case:

http://dpaste.dzfl.pl/fd3bc2a839a3

On Thursday, 10 March 2016 at 16:51:32 UTC, Andrea Fontana wrote:
> On Thursday, 10 March 2016 at 16:20:42 UTC, Taylor Hillegeist wrote:
>> I feel like this should do what i want it too. but it doesn't.
>>
>> struct Color_t {
>> 	static if(1==1){
>> 		import std.bitmanip:bitfields;
>> 		immutable string item = bitfields!(		
>> 				uint, "R",    8,
>> 				uint, "G",   8,
>> 				uint, "B",    8,
>> 				uint, "A", 8);
>> 	}
>> 	mixin(item);
>> }
>
> I wonder if compiler is smart enaugh to undestand that dependency is not needed at runtime in this case:
>
> http://dpaste.dzfl.pl/fd3bc2a839a3

well the latest gdc isnt smart enough.

immutable(string) BF(){
	if(!__ctfe)
		assert(0);
	import std.bitmanip:bitfields;
	return bitfields!(		
			uint, "R", 8,
			uint, "G", 8,
			uint, "B", 8,
			uint, "A", 8);
}

struct Color_t {
	mixin(BF());
}

is a fair try as well. but neither work.

On Thursday, 10 March 2016 at 17:05:26 UTC, Taylor Hillegeist wrote:
> On Thursday, 10 March 2016 at 16:51:32 UTC, Andrea Fontana wrote:
>> On Thursday, 10 March 2016 at 16:20:42 UTC, Taylor Hillegeist wrote:
>>> [...]
>>
>> I wonder if compiler is smart enaugh to undestand that dependency is not needed at runtime in this case:
>>
>> http://dpaste.dzfl.pl/fd3bc2a839a3
>
> well the latest gdc isnt smart enough.

So interestingly this will work if i add -ffunction-sections  to my compiler options? no idea why?

On Thursday, 10 March 2016 at 17:22:58 UTC, Taylor Hillegeist wrote:
> On Thursday, 10 March 2016 at 17:05:26 UTC, Taylor Hillegeist wrote:
>> On Thursday, 10 March 2016 at 16:51:32 UTC, Andrea Fontana wrote:
>>> On Thursday, 10 March 2016 at 16:20:42 UTC, Taylor Hillegeist wrote:
>>>> [...]
>>>
>>> I wonder if compiler is smart enaugh to undestand that dependency is not needed at runtime in this case:
>>>
>>> http://dpaste.dzfl.pl/fd3bc2a839a3
>>
>> well the latest gdc isnt smart enough.
>
> So interestingly this will work if i add -ffunction-sections  to my compiler options? no idea why?

However my binary goes from 4kb with static text to 11kb with the above change.

On Thursday, 10 March 2016 at 17:24:51 UTC, Taylor Hillegeist wrote:
> On Thursday, 10 March 2016 at 17:22:58 UTC, Taylor Hillegeist wrote:
>> On Thursday, 10 March 2016 at 17:05:26 UTC, Taylor Hillegeist wrote:
>>> On Thursday, 10 March 2016 at 16:51:32 UTC, Andrea Fontana wrote:
>>>> On Thursday, 10 March 2016 at 16:20:42 UTC, Taylor Hillegeist wrote:
>>>>> [...]
>>>>
>>>> I wonder if compiler is smart enaugh to undestand that dependency is not needed at runtime in this case:
>>>>
>>>> http://dpaste.dzfl.pl/fd3bc2a839a3
>>>
>>> well the latest gdc isnt smart enough.
>>
>> So interestingly this will work if i add -ffunction-sections  to my compiler options? no idea why?
>
> However my binary goes from 4kb with static text to 11kb with the above change.

I suppose the linker optimized the functions away since they are now in their own section. But it seems a hacky way to do this.

On Thursday, 10 March 2016 at 17:43:08 UTC, Taylor Hillegeist wrote:
> I suppose the linker optimized the functions away since they are now in their own section. But it seems a hacky way to do this.

AFAIK assert(0) and other falsey assert have a special meaning for compiler.
So probably it's not so hacky but just a way to say that case can't happen.

It is used also for:


auto myfunc(int i)
{

   if (i == 0) return 10;
   else if (i == 1) return 3;

   assert(0);
}

And also with non final switch using

switch(var)
{
   case ...
...
   default: assert(0);
}