injecting imports when compiling

[Rumbu]

On Tuesday, 7 December 2021 at 09:54:40 UTC, WebFreak001 wrote:

> Use cases:
> - small application templates/modes with common imports set 
> (like std.stdio, std.conv, std.algorithm, std.array, 
> std.format) so you can more easily and quickly prototype (C# 10 
> / .NET 6 for example added this with implicit usings, though 
> I'm not a fan because C# is just not that good at quick 
> prototyping like D is)
>

Implicit usings are in fact a IDE feature workaround. Behind the 
scenes, a hidden globalusings.g.cs file is created and added 
silently to the existing project. The file contains several 
```using global``` directives which are a new feature in C# 10. 
You can manually write the same cs file, add it to the project 
and obtain the same effect (as long as you are using C# 10).

The same approach will not work in D because in D each file is a 
module, therefore the only chance is that the compiler read this 
global imports from a configuration file and inject them into 
each module.

On the other hand, placing a simple ```import std``` at the 
beginning of your module will have the same effect.