Implementing swap for user-defined swaps

[ag0aep6g]

On 10/07/2017 07:55 PM, Balagopal Komarath wrote:
>    I was implement my own range type that forwards all accesses to 
> another range. I tried to write a `swap` function so that sort etc. 
> could be called on my range. However, I cannot get 
> `hasSwappableElements!ARange` to evaluate to true. But, when I copy 
> pasted the definition of `hasSwappableElements` into my module and 
> evaluated it, it was true. I assume this is something to do with how 
> name lookup works in D. Here's simplified code that reproduces the same 
> problem.
> 
> https://dpaste.dzfl.pl/48a420cce261

You can't provide your own swap function. `sort` etc. use 
std.algorithm.swap, so your range has to work with that.