Is there an annotation that declares a function compile-time only? I'm attempting to use a mixin string generating function that uses standard druntime imports, but I'm working in a no-stdlib environment. I never need to use this function at runtime (as is the case, I imagine, with a great many of mixin string generating functions) so is there a way I can omit it?

On Friday, 23 June 2017 at 10:46:11 UTC, Moinak Bhattacharyya wrote:
> Is there an annotation that declares a function compile-time only? I'm attempting to use a mixin string generating function that uses standard druntime imports, but I'm working in a no-stdlib environment. I never need to use this function at runtime (as is the case, I imagine, with a great many of mixin string generating functions) so is there a way I can omit it?

There is no such annotation.
However what you can do is to put your function into a function literal and enclose it with if (__ctfe)

which would look like this

string GenString(bla, blubb)
{
  if (__ctfe) {
    auto functionBody = () {
     // .... your body with imports and all
    }
    return functionBody(bla, blubb);
  }
  else
  {
    assert(0);
  }
}

this should hopefully keep the compile-time code out of your executable.
It is even more effective if you use a immediately invoked function literal directly inside the mixin.
which will also cause the symbol for the function to invisible and therefore not generated.

On Friday, 23 June 2017 at 10:52:25 UTC, Stefan Koch wrote:
> string GenString(bla, blubb)

That still keeps string (an associative array) as a runtime symbol thus requires druntime. How can I remove the string-y part?

On Friday, 23 June 2017 at 11:04:52 UTC, Moinak Bhattacharyya wrote:
> On Friday, 23 June 2017 at 10:52:25 UTC, Stefan Koch wrote:
>> string GenString(bla, blubb)
>
> That still keeps string (an associative array) as a runtime symbol thus requires druntime. How can I remove the string-y part?

My mistake, it's typeinfo that's being included now. So is memcpy. I don't know why, as they are never used at runtime. How can I avoid this?

On Friday, 23 June 2017 at 11:24:14 UTC, Moinak Bhattacharyya wrote:

> My mistake, it's typeinfo that's being included now. So is memcpy. I don't know why, as they are never used at runtime. How can I avoid this?

Unless you're using GDC with this (https://github.com/D-Programming-GDC/GDC/pull/456), TypeInfo is always going to be included.

The only way to get a build is write TypeInfo stubs like this (https://github.com/JinShil/minimal_druntime_experiment/blob/master/source/d/runtime/object.d#L51)

If you're trying to use D without the runtime, you're going to have to provide certain implementations depending on which features of D you are using.

Mike

On Friday, 23 June 2017 at 11:29:52 UTC, Mike wrote:
> On Friday, 23 June 2017 at 11:24:14 UTC, Moinak Bhattacharyya wrote:
>
>> My mistake, it's typeinfo that's being included now. So is memcpy. I don't know why, as they are never used at runtime. How can I avoid this?
>
> Unless you're using GDC with this (https://github.com/D-Programming-GDC/GDC/pull/456), TypeInfo is always going to be included.
>
> The only way to get a build is write TypeInfo stubs like this (https://github.com/JinShil/minimal_druntime_experiment/blob/master/source/d/runtime/object.d#L51)
>
> If you're trying to use D without the runtime, you're going to have to provide certain implementations depending on which features of D you are using.
>
> Mike

I think there should be a decoupling of the compile-time and runtime library. When I provide a stub object.d, the compile-time function fails due to missing implementations.

On Friday, 23 June 2017 at 11:50:08 UTC, Moinak Bhattacharyya wrote:

> I think there should be a decoupling of the compile-time and runtime library. When I provide a stub object.d, the compile-time function fails due to missing implementations.

Welcome to the club!

On Friday, 23 June 2017 at 10:46:11 UTC, Moinak Bhattacharyya wrote:
> Is there an annotation that declares a function compile-time only? I'm attempting to use a mixin string generating function that uses standard druntime imports, but I'm working in a no-stdlib environment. I never need to use this function at runtime (as is the case, I imagine, with a great many of mixin string generating functions) so is there a way I can omit it?

I don't know of any way to generate a compile-time error if a function cannot be evaluated at compile-time.  I think you will have to use a manifest constant (https://dlang.org/spec/enum.html#manifest_constants) to force evaluation at compile time.

// If you're not using druntime, you'll have to define the
// string type as an alias to an immutable char array.
// See https://github.com/dlang/druntime/blob/master/src/object.d#L41
alias immutable(char)[] string;

string GenString(string a, string b)
{
    return a ~ ", " ~ b;
}

void main()
{
    // `result` is a manifest constant that contains your
    // compile-time string, do as you wish with it
    enum result = GenString("Hello", "World");
}

On Friday, 23 June 2017 at 12:23:23 UTC, Mike wrote:
> alias immutable(char)[] string;
>
> string GenString(string a, string b)
> {
>     return a ~ ", " ~ b;
> }
>
> void main()
> {
>     // `result` is a manifest constant that contains your
>     // compile-time string, do as you wish with it
>     enum result = GenString("Hello", "World");
> }

The problem is, I have to concat a string with an int thus I need to use std.conv. This creates all sorts of problems. Do i really need to create my own itoa function?

On Friday, 23 June 2017 at 12:29:09 UTC, Moinak Bhattacharyya wrote:
> On Friday, 23 June 2017 at 12:23:23 UTC, Mike wrote:
>> alias immutable(char)[] string;
>>
>> string GenString(string a, string b)
>> {
>>     return a ~ ", " ~ b;
>> }
>>
>> void main()
>> {
>>     // `result` is a manifest constant that contains your
>>     // compile-time string, do as you wish with it
>>     enum result = GenString("Hello", "World");
>> }
>
> The problem is, I have to concat a string with an int thus I need to use std.conv. This creates all sorts of problems. Do i really need to create my own itoa function?

The the one from https://github.com/UplinkCoder/bf-ctfe/blob/master/source/bf_compiler.d
and https://github.com/UplinkCoder/bf-ctfe/blob/master/source/bf_fastmath.d