Sane API design (AKA C's #ifdef hell)

[Dennis]

On Friday, 17 April 2026 at 08:08:57 UTC, Dejan Lekic wrote:
> It becomes _much more_ complicated when you need to check for 
> version, and depending on version declare functions. D does not 
> offer good solution for this and that is where C preprocessor 
> wins as we have to combine `version`s, enums, static ifs in 
> order to achieve things that are quite simple with C 
> preprocessor.
>
> Those who believe D is good for this should write a binding for 
> a complex library that supports all versions.

I'm looking at https://github.com/nigels-com/glew/tree/master and 
https://github.com/BindBC/bindbc-opengl, and I wouldn't say 
either is a winner.

The effort needed to accommodate "complex library" and "all 
versions" by far eclipses the effort to write a little 
boilerplate like:

```D
enum glSupport = (){
	version(GL_46)       return GLSupport.gl46;
	else version(GL_45)  return GLSupport.gl45;
	else version(GL_44)  return GLSupport.gl44;
	else version(GL_43)  return GLSupport.gl43;
	else version(GL_42)  return GLSupport.gl42;
	else version(GL_41)  return GLSupport.gl41;
	else version(GL_40)  return GLSupport.gl40;
	else version(GL_33)  return GLSupport.gl33;
	else version(GL_32)  return GLSupport.gl32;
	else version(GL_31)  return GLSupport.gl31;
	else version(GL_30)  return GLSupport.gl30;
	else                 return GLSupport.gl21;
}();
```
https://github.com/BindBC/bindbc-opengl/blob/d3c00b1cb6b11494ed84bb8d9879eb18baa16d6c/source/bindbc/opengl/config.d#L46-L59

I'm not saying D's version system is all flowers and sunshine, 
but personally I wish people were more keen on solving the "10000 
lines of complex bindings" problem rather than the "100 lines of 
boilerplate" problem. ImportC has lots of potential here, 
although in practice the abundant use of non-standard C 
extensions and macro APIs still necessitates lots of manual work 
unfortunately.