D: How to check if a function is chained? a().b().c();

[Steven Schveighoffer]

On Saturday, 18 November 2023 at 07:47:19 UTC, BoQsc wrote:
> Let's say we have a chain of functions.
> ```
>  a().b().c();
> ```
>
>
> I would like to have a behaviour in `a()` that would check if 
> there is `b()` or `c()` chained to it.
>
> If `a();`is not chained: do a `writeln("You forgot to chain 
> this function!");`
>
> #### A function that executes a program
>
> For me syntactically it is important. One real world 
> application would be:
>
> `program("someProgramName").pipe("someOtherProgramName");`
> Executes and pipes output to another program.
>
> `program();` - Only executes the program.

Consider adding @mustuse on the return type.

https://dlang.org/spec/attribute.html#mustuse-attribute

-Steve