Return type deduction

Timon Gehr via Digitalmars-d digitalmars-d at
Mon Sep 5 16:01:32 PDT 2016

On 05.09.2016 14:31, Adam D. Ruppe wrote:
> On Monday, 5 September 2016 at 09:59:16 UTC, Andrea Fontana wrote:
>> I asked this some time (years?) ago. Time for a second try :)
> Return type deduction probably won't work,

Why? It seems rather easy to do.

> but implicit casts of a
> custom data type could do this - that's how C++ would do it.
> ...

That does not solve the problem that nicely: if no different type is 
specified the dummy object with the opImplicitCast can be assigned to a 

auto x = a.get(); // oops

This shouldn't compile.

> Alas, D does not have an implicit cast operator :( best we have is
> `alias this` but it only allows one right now (despite the book saying
> it is supposed to do multiple.. and there are some PRs about it). They
> wouldn't be templated but json could just do a few implicit casts.

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