Extend the call site default argument expansion mechanism?

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On Friday, 11 May 2018 at 14:26:21 UTC, Jonathan M Davis wrote:
> On Thursday, May 10, 2018 14:15:18 Yuxuan Shui via 
> Digitalmars-d wrote:
>> So in D I can use default argument like this:
>> [...]
>> Is this a good idea?
>
> It seems like really risky move, honestly, because it means 
> that the function is then affected by what is and isn't 
> declared within the scope where it's called. __FILE__ and 
> __LINE__ are well-defined as to what they mean. No can declare 
> them to mean something else. You don't have symbol resolution 
> issues or naming conflicts. And they're solving a problem that 
> can't actually be solved without compiler help. However, if you 
> just want to change what arguments get passed to foo within 
> your module, all you have to do is define another foo inside 
> the module and have it forward to the original one with 
> whatever arguments you want. What you're suggesting here seems 
> to introduce name pollution issues without solving anything 
> that can't easily be solved with the language as-is.
>
> - Jonathan M Davis

I see what you're saying and I agree with you. I think a better 
way would be to try and extend the `with` syntax to work with 
arbitrary functions, rather than only objects. That would make it 
more useful. So something like:

---
void f1(allocator alloc, ...){}
void f2(allocator alloc, ...){}
...
void fn(allocator alloc, ...){}

void main()
{
     with(MyAllocator) {
         f1(...);
         f2(...);
         ...
         fn(...);
     }
}
---