Uniform Function Call Syntax in D - GameDev.net

[Jonathan M Davis]

On Monday, July 02, 2012 07:54:56 dennis luehring wrote:
> Am 02.07.2012 07:13, schrieb Jonathan M Davis:
> > On Monday, July 02, 2012 07:00:23 dennis luehring wrote:
> >> Am 01.07.2012 23:02, schrieb Walter Bright:
> >> > On 7/1/2012 11:53 AM, Nick Sabalausky wrote:
> >> >> That successfully compiles and prints "Member". Same thing happens if
> >> >> you move the UFCS func and Foo definition out into their own separate
> >> >> modules. But I was expecting a conflict error at compile-time. Is this
> >> >> a bug?
> >> > 
> >> > No, it's correct behavior. A real member overrides.
> >> 
> >> isn't that some sort of highjacking then?
> > 
> > More like it avoids hijacking. It stops you from creating a function which
> > is used instead of the one which is on the class or struct.
> > 
> > Granted, this does mean that you could be surprised about your external
> > function not being called, and adding a new member function could cause
> > your existing external function to no longer be called (which could be a
> > problem), but realistically there's no other way to handle the situation.
> > It's possible to explicitly give a path to the free function (e.g.
> > path.to.function), but there's no way to do that for a member function,
> > since there's only one way to call it. So, if you were forced to
> > disambiguate, you could never indicate anything else other than the free
> > function - not without introducing a new syntax to indicate the member
> > function.
> > 
> > - Jonathan M Davis
> 
> but the compiler selects the member-functions silently - thats odd, ok i
> will see it very fast - but then i need to change my code anyway - so
> whats the reason for the silent "overwrite"?

Yes, but as I said, if it _didn't_ select the member function when there was a 
conflict, it would be impossible to call the member function whenever there was 
a conflict. There is no way to indicate that you mean a member function rather 
than a free function. The normal way to do that is to use member function call 
syntax, and UFCS allows you to then use that for free functions. With conflicts 
between free functions, you can do path.to.func or other.place.func instead of 
just func, but with a member function, that's not possible. So, without adding 
new syntax to the language, it was essentially impossible to do anything other 
than pick the member function whenever there's a conflict.

- Jonathan M Davis